WO2006070889A1 - Electric power steering device - Google Patents

Electric power steering device Download PDF

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Publication number
WO2006070889A1
WO2006070889A1 PCT/JP2005/024142 JP2005024142W WO2006070889A1 WO 2006070889 A1 WO2006070889 A1 WO 2006070889A1 JP 2005024142 W JP2005024142 W JP 2005024142W WO 2006070889 A1 WO2006070889 A1 WO 2006070889A1
Authority
WO
WIPO (PCT)
Prior art keywords
internal
teeth
external gear
external
electric power
Prior art date
Application number
PCT/JP2005/024142
Other languages
French (fr)
Japanese (ja)
Inventor
Hiroto Mizutani
Osamu Tatewaki
Original Assignee
Nsk Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nsk Ltd. filed Critical Nsk Ltd.
Priority to JP2006520501A priority Critical patent/JPWO2006070889A1/en
Priority to US10/586,365 priority patent/US20070151794A1/en
Priority to DE112005003002T priority patent/DE112005003002T5/en
Publication of WO2006070889A1 publication Critical patent/WO2006070889A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0421—Electric motor acting on or near steering gear
    • B62D5/0424—Electric motor acting on or near steering gear the axes of motor and final driven element of steering gear, e.g. rack, being parallel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0442—Conversion of rotational into longitudinal movement
    • B62D5/0445—Screw drives
    • B62D5/0448—Ball nuts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/17—Toothed wheels
    • F16H55/171—Toothed belt pulleys
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H7/00—Gearings for conveying rotary motion by endless flexible members
    • F16H7/02—Gearings for conveying rotary motion by endless flexible members with belts; with V-belts
    • F16H7/023—Gearings for conveying rotary motion by endless flexible members with belts; with V-belts with belts having a toothed contact surface or regularly spaced bosses or hollows for slipless or nearly slipless meshing with complementary profiled contact surface of a pulley

Definitions

  • the present invention relates to a ball screw type, separate shaft type rack assist type electric power steering apparatus.
  • an electric power steering apparatus Electric Power Steering, hereinafter referred to as EPS
  • EPS uses an in-vehicle battery as the power source of the electric motor, and since the electric motor with no direct engine drive loss is started only at the steering assist, it can suppress the decrease in driving fuel consumption, and also has electronic control. It has the feature that it can be done very easily.
  • a rack pion type is currently mainstream because of its high rigidity and light weight.
  • the EPS for rack and pion type steering gears includes a column assist type with an electric motor on the side of the column to drive the steering shaft, and an electric ball screw mechanism.
  • a ball screw type rack assist type that drives the rack shaft is also used.
  • the assist force does not act on the mating surface between the pion and the rack, the contact surface pressure between both members, which causes wear and deformation, is relatively small.
  • the male screw groove and ball of the ball screw shaft formed on the rack shaft are engaged via a number of circulating balls (steel balls), and the ball nut is driven to rotate by an electric motor arranged coaxially with the rack shaft or on a separate shaft. As a result, the rack shaft moves in the axial direction.
  • the power transmission mechanism is driven by an electric motor and has a small-diameter external gear having external teeth, and the external gear is inscribed.
  • a ring-shaped internal gear having internal gears that mesh with each other and supported so as to be swingable around the axis of the external gear, a driving pulley provided on the outer peripheral surface of the internal gear, and a belt formed by the driving pulley.
  • a ball screw mechanism that is driven by the driven pulley and moves the rack shaft.
  • Patent Document 1 after the speed is reduced by the external gear and the internal gear, the speed is reduced by the driving pulley and the driven pulley, and the reduction ratio can be increased in two stages. Even if the speed reduction mechanism is not required, or the driven pulley is not increased in diameter, the reduction mechanism as a whole can be reduced in size and achieve a high reduction ratio, and can be easily mounted on a vehicle. Also, since it is not necessary to reduce the radius of curvature of the belt winding region around the driving pulley, the belt life can be extended.
  • Patent Document 1 Japanese Unexamined Patent Application Publication No. 2004-262264 (WO 2004/069631 A1)
  • the present invention has been made in view of the circumstances as described above, and provides an electric power steering device that can improve the durability of teeth and reduce operating noise and operating torque. For the purpose.
  • an auxiliary steering torque is generated from the electric motor, and the auxiliary steering torque is transmitted to the rack shaft of the steering mechanism via the power transmission mechanism.
  • the power transmission mechanism is
  • a ring-shaped internal / external gear having internal teeth that are inscribed in mesh with the external gear, supported so as to be swingable about the axis of the external gear, and having an outer peripheral surface acting as a driving pulley, and the internal / external gear A driven pulley driven via a belt,
  • a ball screw mechanism that is driven by the driven pulley and moves the rack shaft
  • a circular support is provided substantially coaxially,
  • an electric power steering device characterized in that an annular support for supporting the circular support is provided on an end portion of the internal / external gear substantially coaxially and inscribed with the circular support.
  • the outer diameter of the circular support is set substantially equal to the pitch circle diameter of the inner teeth of the external gear
  • An electric power steering device is provided in which the inner diameter of the annular support is set substantially equal to the pitch circle diameter of the internal teeth of the internal and external gears.
  • the circular power support and the annular support have a movement restricting mechanism for restricting the axial movement of the internal and external gears.
  • the outer diameter of the circular support is set substantially equal to the pitch diameter of the external gear
  • An electric power steering device is provided in which the inner diameter of the annular support is set substantially equal to the pitch circle diameter of the internal teeth of the internal and external gears.
  • the movement restricting mechanism is configured such that one of the contact portions of the circular support and the annular support is formed in a convex shape and the other is formed in a concave shape. Is provided.
  • the movement restricting mechanism is provided with an electric power steering device characterized in that the shape of the contact portion between the circular support and the annular support is formed in a tapered shape so as to be opposed and symmetrical.
  • An electric power steering apparatus wherein a flange is provided on a side portion of the internal / external gear.
  • An electric power steering device is provided in which the flange is formed integrally with the annular support provided at an end of the internal / external gear.
  • the external teeth of the external gear, the internal teeth of the internal and external gears and the outer peripheral surface combined teeth, the combined teeth of the belt, and the outer peripheral surface combined teeth of the driven pulley are set to bevel teeth
  • the twist angle of the internal teeth of the internal and external gears is ⁇
  • the twist angle of the outer peripheral surface meshing teeth of the inner and outer gears is ⁇
  • the meshing pitch circle radius of the internal teeth of the internal and external gears is r
  • a lower steering device is provided.
  • An electric power steering device characterized by being used for four-wheel steering rear wheel steering is provided.
  • An electric power steering apparatus is provided that is used for steer-by-wire steering in which the steering wheel and the rack shaft are not mechanically connected.
  • a circular support is provided on the end of the external gear substantially coaxially, and the circular support is supported on the end of the internal and external gears in a coaxial manner.
  • An annular support is provided.
  • the radial force of the tension acting on the drive pulley can be supported by the circular support and the annular support, and both gears can only handle torque transmission.
  • the radial force due to the belt tension does not act on both gears, and the inner and outer gears do not bite into the outer gear. Therefore, the durability strength of the teeth can be improved and the operating noise and operating torque can be reduced.
  • the outer diameter of the circular support is set substantially equal to the pitch circle diameter of the outer gear
  • the inner diameter of the annular support is set substantially equal to the pitch circle diameter of the inner teeth of the inner and outer gears. It is. For this reason, the contact portion between the circular support and the annular support is not rolled in contact with sliding. Since contact occurs, an increase in operating torque due to friction can be minimized.
  • the circular support and the annular support have the movement restricting mechanism that restricts the axial movement of the internal and external gears, and the movement restricting mechanism includes the circular support and the annular ring.
  • the shape of the contact portion with the support one is formed in a convex shape and the other is formed in a concave shape.
  • the concavo-convex shape has, for example, different radii of curvature, and the contact portion has a contact form that is close to a point contact.
  • the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
  • the movement restricting mechanism is formed so that the contact portions of the circular support and the annular support face each other in a tapered shape and are symmetrical.
  • the contact portion is close to point contact and has a contact form. As a result, since the contact portion makes rolling contact with a small area (substantially point contact), friction and wear can be remarkably reduced.
  • the flange is provided on the side portion of the internal and external gears to restrict the axial movement of the belt. This prevents the belt from moving in the axial direction and touching the housing, thereby preventing an increase in operating torque, a decrease in durability, and abnormal noise.
  • the flange is formed integrally with the annular support provided at the end of the internal and external gears, means for attaching the flange separately is omitted, and the thickness of the mounting portion is reduced. Is possible and has the effect of making the structure compact.
  • the belt mesh teeth and the outer peripheral surface mesh teeth of the driven pulley are set as oblique teeth, and the twist directions of these oblique teeth are set to be the same direction.
  • the twist angle of the internal teeth of the internal and external gears is ⁇ , and the outer periphery of the internal and external gears
  • the twist angle of the face meshing teeth is ⁇ , and the meshing pitch circle radius of the internal teeth of the internal and external gears is r.
  • the meshing pitch circle radius between the outer peripheral surface gear teeth of the inner and outer gears and the belt gear teeth is r.
  • the force for axially moving the internal and external gears generated from the meshing of the external teeth of the external gear and the internal teeth of the internal and external gears is set to be equal, and as a result, the axial movement of the inner and outer gears is restricted.
  • FIG. 1 is a longitudinal sectional view of an electric power steering apparatus of a ball screw type and another-shaft rack assist type according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view along the line A—A (dashed line side) in FIG.
  • FIG. 3 is a cross-sectional view taken along line BB (two-dot chain line side) in FIG.
  • FIG. 4 is a longitudinal sectional view of a ball screw type separate-axis rack assist type electric power steering apparatus according to a second embodiment of the present invention.
  • FIG. 5 is an enlarged cross-sectional view showing, in an enlarged manner, a contact portion between a circular support and an annular support according to a second embodiment of the present invention.
  • FIG. 6A An enlarged cross-sectional view showing a contact portion between a circular support and an annular support according to a modification of the second embodiment of the present invention.
  • FIG. 6B is an enlarged cross-sectional view showing, in an enlarged manner, a contact portion between the circular support and the annular support according to a modification of the second embodiment of the present invention.
  • FIG. 6C is an enlarged cross-sectional view showing, in an enlarged manner, the contact portion between the circular support and the annular support according to a modification of the second embodiment of the present invention.
  • FIG. 7 is an enlarged cross-sectional view of a main part of a ball screw type separate-shaft rack assist type electric power steering device according to a third embodiment of the present invention.
  • FIG. 8 is a longitudinal sectional view of a ball screw type separate-axis rack assist type electric power steering device according to a fourth embodiment of the present invention.
  • FIG. 9 is a longitudinal sectional view of a ball screw type separate-axis rack assist type electric power steering device according to a fifth embodiment of the present invention.
  • FIG. 10A is an enlarged cross-sectional view of the circular support and the annular support shown in FIG.
  • FIG. 10B is an enlarged cross-sectional view of a circular support and an annular support according to a sixth embodiment of the present invention.
  • FIG. 10C is an enlarged cross-sectional view of a circular support and an annular support according to a seventh embodiment of the present invention.
  • FIG. 11 is a vertical cross-sectional view of a ball screw type separate-shaft rack assist type electric power steering apparatus according to an embodiment of the present invention.
  • FIG. 12A is a schematic diagram showing an enlarged view of a meshing portion of the external gear, the internal / external gear, and the belt shown in FIG. 11.
  • FIG. 12B The meshing pitch line (X) between the external teeth of the external gear and the internal teeth of the internal and external gears is indicated by a broken line, and the meshing pitch line of the external surface meshing teeth of the internal and external gears and the meshing teeth of the belt (Y) FIG.
  • FIG. 1 is a longitudinal sectional view of an electric power steering device of a ball screw type and a separate axis type rack assist type according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view taken along the line AA (dotted line) in FIG.
  • FIG. 3 is a cross-sectional view taken along the line BB (two-dot chain line side) in FIG.
  • housings 1, 2, 3 (steering gear cases) are provided, and an electric motor 4 is attached to the nosing and udging 1.
  • the pivot shaft 7 is spline-fitted to the concave end portion of the drive shaft 5 of the electric motor 4.
  • the pivot 7 is rotatably supported on the housings 1 and 2 by bearings 8 and 9.
  • a small-diameter external gear 11 having external teeth is formed on the pivot shaft 7. As shown in FIG. 2, a ring-shaped internal / external gear 12 having internal teeth is meshed with the external gear 11.
  • the internal and external gears 12 are supported so as to be swingable about the axis of the external gear 11, and the outer peripheral surface acts as a driving pulley (that is, the outer peripheral surface of the internal and external gears 12 has , Belt to be described later
  • a belt 14 having meshing teeth on the inside is provided. It's hanging over.
  • a rack shaft 21 is accommodated so as to be movable in the axial direction, and the rack shaft 21 is provided with a ball screw mechanism including a ball nut 22. It is.
  • the rack shaft 21 is formed with a male screw groove 23, while the ball nut 22 is formed with a female screw groove 24.
  • a circular ball is formed between the male screw groove 23 and the female screw groove 24.
  • a large number of steel balls 25 are interposed.
  • the ball nut 22 is provided with a circulation top (not shown) for circulating the steel ball 25.
  • the ball nut 22 is supported by a double row bearing 26, and is connected so that the driven pulley 13 can rotate together with the ball nut 22 at a spline portion 28 provided on the cylindrical body 27 at the end thereof. is there.
  • circular support bodies 31 are provided on both ends of the outer gear 11 on substantially the same axis, and both ends of the inner and outer gears 12 are provided.
  • a circle on the same axis An annular support 32 that supports the support 31 inwardly is provided.
  • the radial force of the tension acting on the outer peripheral surface of the internal / external gear 12 can be supported by the circular support 31 and the annular support 32, and both the gears 11 and 12 can transmit only torque. Can take charge.
  • the radial force due to the belt tension does not act on the gears 11 and 12, and the inner and outer gears 12 do not bite into the outer gear 11. Therefore, the durability strength of the teeth can be improved and the operating noise and operating torque can be reduced.
  • the circular support 31 has an outer diameter set substantially equal to the pitch circle diameter of the outer gear 11
  • the annular support 32 has an inner diameter of the pitch circle diameter of the inner teeth of the inner / outer gear 12. Is set approximately equal to. Therefore, the contact portion between the circular support 31 and the annular support 32 becomes a rolling contact rather than a contact with slipping, so that an increase in operating torque due to friction can be minimized.
  • the inner / outer gear 12 is not provided with a flange, and the bearing that supports the driven pulley 13 when the belt 14 rotates and moves in the axial direction. N Sides of the belt 14 may come into contact with the housings 1 and 2.
  • the circular support 31 and the annular support 32 include an internal and external gear.
  • Embodiments having a movement restricting mechanism that restricts twelve axial movements will be described in detail as second to fourth embodiments.
  • the circular support 31 and the annular support 32 have a movement restricting mechanism that restricts the axial movement of the inner and outer gears 12.
  • the outer peripheral surface of the circular support 31 is formed in a concave arc shape, and the inner peripheral surface of the annular support 32 is a convex arc shape. Is formed.
  • the external gear 11 is rotated by the rotation of the drive shaft 5 of the electric motor 4, and the rotation thereof. Is transmitted to the inner / outer gear 12 and is transmitted to the driven pulley 13 via the belt 14.
  • the belt 14 tends to move in the axial direction due to the orientation and inclination of the core wire, the twist of the belt 14 itself, and the like.
  • the internal / external gear 12 also attempts to move in the axial direction by the rotational force of the belt 14.
  • the outer peripheral surface of the circular support 31 is formed in a concave arc shape
  • the inner peripheral surface of the annular support 32 is formed in a convex arc shape
  • the internal / external gear 12 Is always pressed in the direction of the driven pulley 13 by the belt tension.
  • the concavo-convex arc shape plays a role of guiding, and the axial movement of the internal / external gear 12 can be restricted, and the contact between the internal / external gear 12 and the housings 1, 2, etc. can be avoided.
  • the concavo-convex shape has, for example, different contact radii, and the contact portion between the circular support 31 and the annular support 32 has a contact form close to point contact.
  • the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
  • the uneven shape of the circular support 31 and the annular support 32 only needs to be able to regulate the axial movement of the internal / external gear 12.
  • the concavo-convex shape of the circular support 31 and the annular support 32 is not necessarily a curved surface, but may be formed so as to be in contact with a substantially obtuse angle.
  • the circular support 31 and the annular support 32 may have the directions of the concave and convex arc shapes reversed.
  • a plurality of contact portions in an uneven arc shape may be provided.
  • FIG. 7 is an enlarged cross-sectional view of a main part of a ball screw type, separate-axis rack assist type electric power steering apparatus according to a third embodiment of the present invention.
  • the circular support 31 and the annular support 32 are arranged so that the internal and external gears 12 move in the axial direction. It has a movement regulation mechanism that regulates movement.
  • the contact portions of the circular support 31 and the annular support 32 are opposed to each other as a tapered shape, and are formed symmetrically.
  • the shape of the contact portion between the circular support 31 and the annular support 32 is tapered.
  • the internal and external gears 12 are always pressed against the driven pulley 13 by tension.
  • the contact portion with 32 is in a contact form that is close to point contact. Accordingly, the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
  • FIG. 8 is a longitudinal sectional view of a ball screw type, separate-axis rack assist type electric power steering apparatus according to a fourth embodiment of the present invention.
  • the meshing teeth on the outer peripheral surface of the internal / external gear 12 and the meshing teeth on the outer peripheral surface of the driven pulley 13 provided coaxially with the rack shaft 21 described later are meshed inward.
  • An inclined belt 41 having teeth is stretched over.
  • the inclined tooth belt 41 When the rotation of the internal / external gear 12 is transmitted to the driven pulley 13 via the inclined tooth belt 41, the inclined tooth belt 41 has the inclined tooth angle, the direction and inclination of the core wire, the twist of the inclined tooth belt 41 itself, etc. Tries to move in the axial direction. Also in the present embodiment, when the inclined belt 41 tries to move in the axial direction, the outer peripheral surface of the circular support 31 is formed in a concave arc shape, and the outer peripheral surface of the annular support 32 is The inner and outer gears 12 are always pressed in the direction of the driven pulley 13 by the belt tension.
  • the concavo-convex arc shape plays a role of guiding, the axial movement of the internal / external gear 12 can be restricted, and the contact between the internal / external gear 12 and the housings 1, 2, etc. can be avoided.
  • the concave and convex shapes of the concave and convex shapes are, for example, different contact radii, and the contact portions of the circular support 31 and the annular support 32 and the contact portions are substantially close to point contact. As a result, the frictional wear can be significantly reduced by the rolling contact of the contact portion with a small area (substantially point contact).
  • flanges for restricting axial movement of the belt are provided on both sides of the internal and external gears. I will explain.
  • the external gear 11 is rotated by the rotation of the drive shaft 5 of the electric motor 4, and the rotation is transmitted to the internal / external gear 12 and is transmitted to the driven pulley 13 via the belt 14.
  • the belt 14 tries to move in the axial direction due to the orientation and inclination of the core wire and the twist of the belt 14 itself. If the belt 14 is an inclined belt (not shown), the belt 14 moves in the axial direction depending on the angle of the inclined teeth.
  • the bell A flange 40 is provided to restrict the axial movement of the G14.
  • FIG. 10B is an enlarged cross-sectional view of a circular support and an annular support according to the sixth embodiment of the present invention.
  • the flange 40 is formed integrally with the annular support 32 provided at the end of the internal / external gear 12.
  • the flange 40 is formed integrally with the annular support 32, the means for attaching the flange separately can be omitted, and the thickness of the attachment portion can be reduced. It has the effect of making the structure compact.
  • FIG. 10C is an enlarged cross-sectional view of a circular support and an annular support according to the seventh embodiment of the present invention.
  • the flange 40 is formed integrally with the annular support 32 provided at the end of the internal / external gear 12.
  • the flange 40 is formed integrally with the annular support body 32, means for attaching the flange separately can be omitted, and the thickness of the attachment portion can be reduced. It has the effect of making the structure compact.
  • the circular support 31 and the annular support 32 have a movement restricting mechanism that restricts the axial movement of the internal / external gear 12.
  • the movement restricting mechanism is The outer peripheral surface is formed in a concave arc shape, and the inner peripheral surface of the annular support body 32 is formed in a convex arc shape.
  • the outer peripheral surface of the circular support 31 is formed in a concave arc shape
  • the inner peripheral surface of the annular support 32 is formed in a convex arc shape
  • the inner / outer gear 12 is always driven side It is pressed against the pulley 13 by the belt tension.
  • the concavo-convex arc shape serves as a guide, and the axial movement of the inner / outer gear 12 can be restricted, and contact between the inner / outer gear 12 and the housings 1, 2, etc. can be avoided. Accordingly, an increase in operating torque and a decrease in durability due to sliding contact can be suppressed, and abnormal noise can be prevented.
  • the concavo-convex shape has, for example, different radii of curvature, and the contact portion between the circular support 31 and the annular support 32 has a contact form close to point contact.
  • the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
  • the uneven shape of the circular support 31 and the annular support 32 only needs to be able to restrict the axial movement of the internal / external gear 12.
  • the concavo-convex shape of the circular support 31 and the annular support 32 may be a concavo-convex shape that is not a curved surface, and may be formed so as to be in contact with a substantially obtuse angle.
  • the circular support 31 and the circular support 32 may have reverse concave and convex arc shapes.
  • the external teeth of the external gear, the internal teeth of the internal and external gears and the outer peripheral surface of the external teeth in the above-described first to seventh embodiments, the toothed teeth of the belt, and the teeth of the outer peripheral surface of the driven pulley are: In the first to third embodiments, examples using straight teeth have been described, but inclined teeth may be used as in the fourth embodiment. (Eighth embodiment)
  • those teeth are set as oblique teeth, and the twisting directions of the inclined teeth are set in the same direction.
  • the embodiment will be described in detail below.
  • FIG. 11 is a longitudinal sectional view of an electric power steering device of a ball screw type and another-shaft type rack assist type according to an embodiment of the present invention.
  • FIG. 12A is an enlarged view of the meshing portion of the external gear, the internal / external gear, and the belt shown in FIG. FIG. 12B shows a meshing pitch line (X) between the external teeth of the external gear and the internal teeth of the internal / external gear by a broken line
  • FIG. FIG. 5 is a schematic diagram showing the mating pitch line as a solid line (Y).
  • the external teeth of the external gear 11, the internal teeth 12a and the outer peripheral surface meshing teeth 12b of the internal and external gear 12, the meshing teeth of the belt 14, and the driven pulley 13 The peripheral teeth of the outer teeth are set to be inclined teeth, and the torsional directions of these inclined teeth are set to be the same direction.
  • a tangential force (Fa) is generated in the internal / external gear 12 due to the meshing between the external teeth of the external gear 11 and the internal teeth 12a of the internal / external gear 12.
  • a tangential force (Fb) is generated in the inner / outer gear 12 due to the engagement between the outer peripheral surface meshing teeth 12b of the inner / outer gear 12 and the meshing teeth of the belt 14.
  • the axial direction moving force for axially moving the internal / external gear 12 generated from the meshing between the external teeth of the external gear 11 and the internal teeth 12a of the internal / external gear 12, and the internal / external gear 12 The axial movement force for axially moving the internal / external gear 12 generated by the meshing of the outer peripheral surface meshing teeth 12b of the belt 14 and the meshing teeth of the belt 14 can be set to be opposite to each other. As a result, the axial movement of the inner / outer gear 12 can be restricted.
  • twist angle of the internal teeth 12a of the internal / external gear 12 is ⁇ , and the outer peripheral surface of the internal / external gear 12 is meshed.
  • the tangential force (Fa, Fb) is also the torque force acting on the mating part, respectively.
  • Equation (1) Equation (1) becomes
  • the axial movement of the internal / external gear 12 can be restricted, and an increase in operating torque and a decrease in durability can be suppressed, and the occurrence of abnormal noise can be prevented.
  • the electric power steering device described above may be used to steer the front wheels like a normal steering mechanism, and may be used to steer front wheels or rear wheels of a four-wheel steering mechanism. It is natural.
  • the present invention can also be applied to a so-called steer-by-wire (SBW) type steering in which the steering wheel and the rack shaft are not mechanically connected.
  • SBW steer-by-wire
  • the present invention also includes a combination of the first to eighth embodiments.
  • the radial force of the belt tension acting on the internal and external gears can be supported by the circular support and the annular support, and both gears receive only torque transmission. Can have. Therefore, the radial force due to the belt tension does not act on both gears, and the internal and external gears do not bite into the external gear. Therefore, an electric power steering apparatus that can reduce the operation noise and the operation torque with high tooth durability is provided.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Steering Mechanism (AREA)
  • Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
  • Gear Transmission (AREA)
  • Transmission Devices (AREA)
  • Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)

Abstract

An electric power steering device, comprising a power transmission mechanism driven by an electric motor and having a small diameter external gear with external teeth, a ring-shaped internal/external gear having internal teeth meshing with the external teeth of the external gear in internal contact with each other, supported swingably about the axis of the external gear, and having an outer peripheral surface acting as a drive side pulley, a driven side pulley driven by the internal/ external gear through a belt, and a ball screw mechanism driven by the driven side pulley to move a rack shaft. A circular support body is roughly coaxially formed at the end part of the external gear, and an annular support body supporting the circular support body in internal contact with the circular support body is roughly coaxially formed at the end part of the internal/external gear.

Description

明 細 書  Specification
電動パワーステアリング装置  Electric power steering device
技術分野  Technical field
[0001] 本発明は、ボールねじ式で別軸式ラックアシスト型の電動パワーステアリング装置 に関する。  TECHNICAL FIELD [0001] The present invention relates to a ball screw type, separate shaft type rack assist type electric power steering apparatus.
背景技術  Background art
[0002] 自動車の操舵系では、外部動力源を用いて操舵アシストを行わせる、いわゆるパヮ 一ステアリング装置が広く採用されている。従来、パワーステアリング装置用の動力 源としては、ベーン方式の油圧ポンプが用いられており、この油圧ポンプをエンジン により駆動するものが多力つた。ところが、この種のパワーステアリング装置は、油圧 ポンプを常時駆動することによるエンジンの駆動損失が大きい (最大負荷時において 、数馬力〜十馬力程度)ため、小排気量の軽自動車等への採用が難しぐ比較的大 排気量の自動車でも走行燃費が無視できな 、ほど低下することが避けられな力つた  [0002] In a steering system of an automobile, a so-called power steering apparatus that performs steering assist using an external power source is widely adopted. Conventionally, vane type hydraulic pumps have been used as power sources for power steering systems, and many of these are driven by engines. However, this type of power steering system has a large engine drive loss due to the constant driving of the hydraulic pump (several horsepower to about 10 horsepower at the maximum load). Even with difficult and relatively large-displacement cars, it is inevitable that the fuel economy will not be negligible, even if the driving fuel consumption is negligible.
[0003] そこで、これらの問題を解決するものとして、電動モータを動力源とする電動パワー ステアリング装置（Electric Power Steering,以下 EPSと記す）が近年注目されている 。 EPSには、電動モータの電源に車載バッテリを用いるために直接的なエンジンの 駆動損失が無ぐ電動モータが操舵アシスト時にのみに起動されるために走行燃費 の低下も抑えられる他、電子制御が極めて容易に行える等の特長がある。 [0003] In order to solve these problems, an electric power steering apparatus (Electric Power Steering, hereinafter referred to as EPS) using an electric motor as a power source has attracted attention in recent years. EPS uses an in-vehicle battery as the power source of the electric motor, and since the electric motor with no direct engine drive loss is started only at the steering assist, it can suppress the decrease in driving fuel consumption, and also has electronic control. It has the feature that it can be done very easily.
[0004] 一方、乗用車用のステアリングギヤとしては、高剛性かつ軽量であること等から、現 在ではラックピ-オン式が主流となっている。そして、ラック &ピ-オン式ステアリング ギヤ用の EPSとしては、ステアリングシャフトゃピ-オン自体を駆動するべくコラム側 部に電動モータを配置したコラムアシスト型等の他、電動式のボールねじ機構により ラック軸を駆動するボールねじ式ラックアシスト型も用いられて 、る。ボールねじ式ラ ックアシスト型の EPSでは、アシスト力がピ-オンとラックとの嚙合面に作用しないた め、摩耗や変形の要因となる両部材間の接触面圧が比較的小さくなる。  [0004] On the other hand, as a steering gear for a passenger car, a rack pion type is currently mainstream because of its high rigidity and light weight. The EPS for rack and pion type steering gears includes a column assist type with an electric motor on the side of the column to drive the steering shaft, and an electric ball screw mechanism. A ball screw type rack assist type that drives the rack shaft is also used. In the ball screw rack assist type EPS, since the assist force does not act on the mating surface between the pion and the rack, the contact surface pressure between both members, which causes wear and deformation, is relatively small.
[0005] ラックアシスト型 EPSでは、ラック軸に形成されたボールねじ軸の雄ねじ溝とボール ナットに形成された雌ねじ溝とが多数個の循環ボール (鋼球)を介して係合しており、 ラック軸と同軸あるいは別軸に配置された電動モータによってボールナットが回転駆 動され、これにより、ラック軸が軸方向に移動する。 [0005] In the rack assist type EPS, the male screw groove and ball of the ball screw shaft formed on the rack shaft. The female thread groove formed in the nut is engaged via a number of circulating balls (steel balls), and the ball nut is driven to rotate by an electric motor arranged coaxially with the rack shaft or on a separate shaft. As a result, the rack shaft moves in the axial direction.
[0006] また、別軸式ラックアシスト型 EPSにおける電動モータとボールナットとの間の動力 伝達方法としては、ギヤ式、タイミングベルト式等が一般的である。  [0006] Further, as a power transmission method between the electric motor and the ball nut in the separate-shaft rack assist type EPS, a gear type, a timing belt type, and the like are generally used.
[0007] ところで、特許文献 1では、別軸式ラックアシスト型 EPSに於 、て、動力伝達機構は 、電動モータにより駆動され、外歯を有する小径の外歯車と、この外歯車を内接して 嚙合する内歯を有し、外歯車の軸線を中心に揺動可能に支持されるリング状の内歯 車と、この内歯車の外周面に設けた駆動側プーリと、この駆動側プーリによりベルトを 介して駆動される従動側プーリと、この従動側プーリにより駆動されて、ラック軸を移 動させるボールねじ機構と、を備えている。  By the way, in Patent Document 1, in the separate-shaft rack assist type EPS, the power transmission mechanism is driven by an electric motor and has a small-diameter external gear having external teeth, and the external gear is inscribed. A ring-shaped internal gear having internal gears that mesh with each other and supported so as to be swingable around the axis of the external gear, a driving pulley provided on the outer peripheral surface of the internal gear, and a belt formed by the driving pulley. And a ball screw mechanism that is driven by the driven pulley and moves the rack shaft.
[0008] このように、特許文献 1では、外歯車と内歯車により減速した後、駆動側プーリと従 動側プーリにより減速しており、 2段階で減速比を稼げるので、駆動側プーリを小径 化したり、又は、従動側プーリを大径ィ匕しなくても、減速機構を全体として、小型で高 い減速比を達成することができ、車両への搭載性を良くすることができる。し力も、駆 動側プーリへのベルトの巻き掛け領域の曲率半径を小さくする必要がないので、ベ ルトの寿命を長くすることができる。  As described above, in Patent Document 1, after the speed is reduced by the external gear and the internal gear, the speed is reduced by the driving pulley and the driven pulley, and the reduction ratio can be increased in two stages. Even if the speed reduction mechanism is not required, or the driven pulley is not increased in diameter, the reduction mechanism as a whole can be reduced in size and achieve a high reduction ratio, and can be easily mounted on a vehicle. Also, since it is not necessary to reduce the radius of curvature of the belt winding region around the driving pulley, the belt life can be extended.
[0009] また、特許文献 1では、駆動側プーリの両端に設けたハウジングと一体の案内部に よって、駆動側プーリの軸方向移動を規制している。  [0009] Also, in Patent Document 1, axial movement of the driving pulley is restricted by guide portions integral with the housing provided at both ends of the driving pulley.
特許文献 1 :特開 2004— 262264号公報（WO 2004/069631 A1)  Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-262264 (WO 2004/069631 A1)
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0010] ところで、特許文献 1では、ベルトを掛け渡した駆動側プーリに作用するベルト張力 のうち、ラジアル方向の力（以下、ラジアル力）は、外歯車と内歯車との歯面で受ける ことになる。 [0010] By the way, in Patent Document 1, of the belt tension acting on the drive pulley over which the belt is stretched, the radial force (hereinafter referred to as radial force) is received by the tooth surfaces of the external gear and the internal gear. become.
[0011] その結果、通常の歯車減速機であれば、一枚の歯に注目した場合、歯の片側のみ で接触するが、この場合には、外歯車と内歯車との歯の両面にて接触し、内歯車が 外歯車に食い込む形となり、歯の耐久強度の低下を招来し、作動音や作動トルクの 増加を招来すると 、つたことがある。 As a result, in the case of a normal gear reducer, when attention is paid to one tooth, contact is made only on one side of the tooth, but in this case, both sides of the tooth of the external gear and the internal gear are contacted. Contact, the internal gear bites into the external gear, which reduces the durability of the teeth and reduces the operating noise and torque. There has been an increase in inviting an increase.
[0012] 本発明は、上述したような事情に鑑みてなされたものであって、歯の耐久強度を向 上し、作動音や作動トルクを低減することができる、電動パワーステアリング装置を提 供することを目的とする。  The present invention has been made in view of the circumstances as described above, and provides an electric power steering device that can improve the durability of teeth and reduce operating noise and operating torque. For the purpose.
課題を解決するための手段  Means for solving the problem
[0013] 上記の目的を達成するため、本発明の第 1の側面によれば、 [0013] In order to achieve the above object, according to a first aspect of the present invention,
ステアリングホイールに印加した操舵トルクに対応して、電動モータから補助操舵ト ルクを発生させ、動力伝達機構を介して、操舵機構のラック軸に前記補助操舵トルク を伝達する別軸式ラックアシスト型の電動パワーステアリング装置において、 前記動力伝達機構は、  In response to the steering torque applied to the steering wheel, an auxiliary steering torque is generated from the electric motor, and the auxiliary steering torque is transmitted to the rack shaft of the steering mechanism via the power transmission mechanism. In the electric power steering apparatus, the power transmission mechanism is
前記電動モータにより駆動され、外歯を有する小径の外歯車と、  A small-diameter external gear driven by the electric motor and having external teeth;
当該外歯車に内接して嚙合する内歯を有し、当該外歯車の軸線を中心に揺動可 能に支持され、外周面が駆動側プーリとして作用するリング状の内外歯車と、 当該内外歯車により、ベルトを介して駆動される従動側プーリと、  A ring-shaped internal / external gear having internal teeth that are inscribed in mesh with the external gear, supported so as to be swingable about the axis of the external gear, and having an outer peripheral surface acting as a driving pulley, and the internal / external gear A driven pulley driven via a belt,
当該従動側プーリにより駆動されて、ラック軸を移動させるボールねじ機構と、を備 え、  A ball screw mechanism that is driven by the driven pulley and moves the rack shaft,
前記外歯車の端部に、略同軸上に、円形支持体が設けてあり、  At the end of the external gear, a circular support is provided substantially coaxially,
前記内外歯車の端部に、略同軸上に、前記円形支持体と内接して前記円形支持 体を支持する円環支持体が設けてあることを特徴とする電動パワーステアリング装置 が提供される。  There is provided an electric power steering device characterized in that an annular support for supporting the circular support is provided on an end portion of the internal / external gear substantially coaxially and inscribed with the circular support.
[0014] 本発明の第 1の側面に力かる本発明の第 2の側面によれば、  [0014] According to the second aspect of the present invention, which works on the first aspect of the present invention,
前記円形支持体は、その外径が前記外歯車の内歯のピッチ円直径に略等しく設定 してあり、  The outer diameter of the circular support is set substantially equal to the pitch circle diameter of the inner teeth of the external gear,
前記円環支持体は、その内径が前記内外歯車の内歯のピッチ円直径に略等しく設 定してあることを特徴とした電動パワーステアリング装置が提供される。  An electric power steering device is provided in which the inner diameter of the annular support is set substantially equal to the pitch circle diameter of the internal teeth of the internal and external gears.
[0015] 本発明の第 1の側面に力かる本発明の第 3の側面によれば、 [0015] According to the third aspect of the present invention, which works on the first aspect of the present invention,
前記円形支持体と前記円環支持体とは、前記内外歯車の軸方向移動を規制する 移動規制機構を有することを特徴とした電動パワーステアリング装置が提供される。 [0016] 本発明の第 3の側面に力かる本発明の第 4の側面によれば、 The circular power support and the annular support have a movement restricting mechanism for restricting the axial movement of the internal and external gears. [0016] According to the fourth aspect of the present invention, which works on the third aspect of the present invention,
前記円形支持体は、その外径が前記外歯車のピッチ円直径に略等しく設定してあ り、  The outer diameter of the circular support is set substantially equal to the pitch diameter of the external gear,
前記円環支持体は、その内径が前記内外歯車の内歯のピッチ円直径に略等しく設 定してあることを特徴とした電動パワーステアリング装置が提供される。  An electric power steering device is provided in which the inner diameter of the annular support is set substantially equal to the pitch circle diameter of the internal teeth of the internal and external gears.
[0017] 本発明の第 3の側面に力かる本発明の第 5の側面によれば、 [0017] According to the fifth aspect of the present invention, which works on the third aspect of the present invention,
前記移動規制機構は、前記円形支持体と前記円環支持体との接触部の形状を、 一方を凸形状に形成し、他方を凹形状に形成してあることを特徴とした電動パワース テアリング装置が提供される。  In the electric power steering apparatus, the movement restricting mechanism is configured such that one of the contact portions of the circular support and the annular support is formed in a convex shape and the other is formed in a concave shape. Is provided.
[0018] 本発明の第 3の側面に力かる本発明の第 6の側面によれば、 [0018] According to the sixth aspect of the present invention, which works on the third aspect of the present invention,
前記移動規制機構は、前記円形支持体と前記円環支持体との接触部の形状を、 テーパ形状として対向し、且つ、対称に形成してあることを特徴とした電動パワーステ ァリング装置が提供される。  The movement restricting mechanism is provided with an electric power steering device characterized in that the shape of the contact portion between the circular support and the annular support is formed in a tapered shape so as to be opposed and symmetrical. The
[0019] 本発明の第 1の側面に力かる本発明の第 7の側面によれば、 [0019] According to the seventh aspect of the present invention, which works on the first aspect of the present invention,
前記内外歯車の側部に、フランジが設けてあることを特徴とした電動パワーステアリ ング装置が提供される。  An electric power steering apparatus is provided, wherein a flange is provided on a side portion of the internal / external gear.
[0020] 本発明の第 7の側面に力かる本発明の第 8の側面によれば、 [0020] According to the eighth aspect of the present invention, which works on the seventh aspect of the present invention,
前記フランジは、前記内外歯車の端部に設けた前記円環支持体に一体的に形成 してあることを特徴とした電動パワーステアリング装置が提供される。  An electric power steering device is provided in which the flange is formed integrally with the annular support provided at an end of the internal / external gear.
[0021] 本発明の第 1の側面に力かる本発明の第 9の側面によれば、 [0021] According to a ninth aspect of the present invention that works on the first aspect of the present invention,
前記外歯車の外歯、前記内外歯車の内歯及び外周面嚙合歯、前記ベルトの嚙合 歯、及び前記従動側プーリの外周面嚙合歯は、斜歯に設定してあり、  The external teeth of the external gear, the internal teeth of the internal and external gears and the outer peripheral surface combined teeth, the combined teeth of the belt, and the outer peripheral surface combined teeth of the driven pulley are set to bevel teeth,
これらの斜歯の捩れ方向は、同一方向になるように設定してあることを特徴とした電 動パワーステアリング装置が提供される。  There is provided an electric power steering apparatus characterized in that the twisting directions of these inclined teeth are set to be the same direction.
[0022] 本発明の第 9の側面に力かる本発明の第 10の側面によれば、 [0022] According to the tenth aspect of the present invention, which works on the ninth aspect of the present invention,
前記内外歯車の内歯の捩れ角は、 Θ であり、  The twist angle of the internal teeth of the internal and external gears is Θ,
a  a
前記内外歯車の外周面嚙合歯の捩れ角は、 Θ であり、  The twist angle of the outer peripheral surface meshing teeth of the inner and outer gears is Θ,
b  b
前記内外歯車の内歯の嚙合いピッチ円半径は、 rであり、  The meshing pitch circle radius of the internal teeth of the internal and external gears is r,
a 前記内外歯車の外周面嚙合歯と前記ベルトの嚙合歯との嚙合いピッチ円半径は、 rであり、以下の関係を満たすべく 0 , Θ , r , rが設定されることを特徴とした電動 b a b a b a The electric pitch circle radius of the outer peripheral surface meshing teeth of the internal and external gears and the meshing teeth of the belt is r, and 0, Θ, r, r are set to satisfy the following relationship: babab
ノ ワーステアリング装置が提供される。  A lower steering device is provided.
[0023] (式 4) tan ^ ra tan ^ 本発明の第 1の側面に力かる本発明の第 11の側面によれば、 [0023] (Equation 4) tan ^ r a tan ^ According to the eleventh aspect of the present invention, which works on the first aspect of the present invention,
4輪操舵の後輪操舵に用いることを特徴とした電動パワーステアリング装置が提供 される。  An electric power steering device characterized by being used for four-wheel steering rear wheel steering is provided.
[0024] 本発明の第 1の側面に力かる本発明の第 12の側面によれば、  [0024] According to the twelfth aspect of the present invention, which works on the first aspect of the present invention,
前記ステアリングホイールと前記ラック軸とが機械的に連結されていない、 ステアバイワイヤ式のステアリングに用いられることを特徴とした電動パワーステアリン グ装置が提供される。  An electric power steering apparatus is provided that is used for steer-by-wire steering in which the steering wheel and the rack shaft are not mechanically connected.
発明の効果  The invention's effect
[0025] 本発明によれば、外歯車の端部に、略同軸上に、円形支持体が設けてあり、内外 歯車の端部に、略同軸上に、円形支持体を内接して支持する円環支持体が設けて ある。  [0025] According to the present invention, a circular support is provided on the end of the external gear substantially coaxially, and the circular support is supported on the end of the internal and external gears in a coaxial manner. An annular support is provided.
[0026] そのため、駆動側プーリに作用する張力のうちのラジアル力は、円形支持体と円環 支持体とにより支持することができ、両歯車は、トルク伝達のみを受け持つことができ る。  [0026] Therefore, the radial force of the tension acting on the drive pulley can be supported by the circular support and the annular support, and both gears can only handle torque transmission.
[0027] 従って、両歯車には、ベルトの張力によるラジアル力は、作用せず、内外歯車が外 歯車に食い込む事がない。よって、歯の耐久強度を向上し、作動音や作動トルクを 低減することができる。  Accordingly, the radial force due to the belt tension does not act on both gears, and the inner and outer gears do not bite into the outer gear. Therefore, the durability strength of the teeth can be improved and the operating noise and operating torque can be reduced.
[0028] また、円形支持体は、その外径が外歯車のピッチ円直径に略等しく設定してあり、 円環支持体は、その内径が内外歯車の内歯のピッチ円直径に略等しく設定してある 。そのため、円形支持体と円環支持体の接触部は、滑りを伴う接触ではなぐ転がり 接触となるので、摩擦に伴う作動トルクの増加を最小限に抑えることができる。 [0028] Further, the outer diameter of the circular support is set substantially equal to the pitch circle diameter of the outer gear, and the inner diameter of the annular support is set substantially equal to the pitch circle diameter of the inner teeth of the inner and outer gears. It is. For this reason, the contact portion between the circular support and the annular support is not rolled in contact with sliding. Since contact occurs, an increase in operating torque due to friction can be minimized.
[0029] 更に本発明によれば、円形支持体と円環支持体は、内外歯車の軸方向移動を規 制する移動規制機構を有しており、移動規制機構は、円形支持体と円環支持体との 接触部の形状を、一方を凸形状に形成し、他方を凹形状に形成してある。  Furthermore, according to the present invention, the circular support and the annular support have the movement restricting mechanism that restricts the axial movement of the internal and external gears, and the movement restricting mechanism includes the circular support and the annular ring. As for the shape of the contact portion with the support, one is formed in a convex shape and the other is formed in a concave shape.
[0030] このような凹凸形状によって、内外歯車の軸方向移動を規制することができ、内外 歯車とハウジング等との接触を回避することができる。  [0030] With such an uneven shape, axial movement of the internal and external gears can be restricted, and contact between the internal and external gears and the housing or the like can be avoided.
[0031] よって、滑り接触による作動トルクの増加や耐久性の低下を抑制すると共に、異音 の発生を防止することが期待できる。  [0031] Therefore, it can be expected that an increase in operating torque and a decrease in durability due to sliding contact are suppressed, and the generation of abnormal noise is prevented.
[0032] し力も、凹凸形状は、例えば、それぞれ異なる曲率半径として、接触部を略点接触 に近い接触形態としている。これにより、接触部が小面積 (略点接触)で転がり接触す ることにより、摩擦'摩耗を著しく低減することができる。 [0032] The concavo-convex shape has, for example, different radii of curvature, and the contact portion has a contact form that is close to a point contact. Thus, the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
[0033] また、移動規制機構は、円形支持体と円環支持体との接触部の形状を、テーパ形 状として対向し、且つ、対称に形成してある。 [0033] Further, the movement restricting mechanism is formed so that the contact portions of the circular support and the annular support face each other in a tapered shape and are symmetrical.
[0034] このようなテーパであって対称的な形状によって、内外歯車の軸方向移動を規制 することができ、内外歯車とハウジング等との接触を回避することができる。 [0034] With such a tapered and symmetric shape, axial movement of the internal and external gears can be restricted, and contact between the internal and external gears and the housing or the like can be avoided.
[0035] 従って、滑り接触による作動トルクの増加や耐久性の低下を抑制すると共に、異音 の発生を防止することができる。 [0035] Therefore, it is possible to suppress an increase in operating torque and a decrease in durability due to sliding contact, and to prevent generation of abnormal noise.
[0036] し力も、テーパであって対称的な形状であることから、接触部を略点接触に近 、接 触形態としている。これにより、接触部が小面積 (略点接触)で転がり接触すること〖こ より、摩擦'摩耗を著しく低減することができる。 [0036] Since the force is also tapered and symmetrical, the contact portion is close to point contact and has a contact form. As a result, since the contact portion makes rolling contact with a small area (substantially point contact), friction and wear can be remarkably reduced.
[0037] また、本発明によれば、内外歯車の側部に、フランジが設けてあり、ベルトの軸方向 移動を規制している。これにより、ベルトが軸方向移動してハウジングなどに接触する ことを回避し、それによる作動トルクの増カロ、耐久性の低下、異音の発生を防止する 効果を有する。  [0037] According to the present invention, the flange is provided on the side portion of the internal and external gears to restrict the axial movement of the belt. This prevents the belt from moving in the axial direction and touching the housing, thereby preventing an increase in operating torque, a decrease in durability, and abnormal noise.
[0038] また、フランジは、内外歯車の端部に設けた円環支持体に一体的に形成してあるこ とから、フランジを別体で取付けるための手段の省略、取付け部の肉厚の低減が可 能であり、構造をコンパクトにする効果を有する。  [0038] Further, since the flange is formed integrally with the annular support provided at the end of the internal and external gears, means for attaching the flange separately is omitted, and the thickness of the mounting portion is reduced. Is possible and has the effect of making the structure compact.
[0039] 更にまた本発明によれば、外歯車の外歯、内外歯車の内歯及び外周面嚙合歯、ベ ルトの嚙合歯、及び従動側プーリの外周面嚙合歯は、斜歯に設定してあり、これらの 斜歯の捩れ方向は、同一方向になるように設定してある。 Furthermore, according to the present invention, the external teeth of the external gear, the internal teeth of the internal / external gear and the outer peripheral surface meshing teeth, The belt mesh teeth and the outer peripheral surface mesh teeth of the driven pulley are set as oblique teeth, and the twist directions of these oblique teeth are set to be the same direction.
[0040] これにより、回転によって、外歯車の外歯と内外歯車の内歯との嚙合いから発生す る内外歯車を軸方向移動させようとする力と、内外歯車の外周面嚙合歯とベルトの嚙 合歯との嚙合いから発生する内外歯車を軸方向移動させようとする力とを、逆向きと なるように設定し、その結果、内外歯車の軸方向移動を規制している。  [0040] Thereby, by the rotation, the force to axially move the internal and external gears generated from the meshing of the external teeth of the external gear and the internal teeth of the internal and external gears, the external surface meshing teeth and the belt of the internal and external gears The force for axially moving the internal and external gears generated from the meshing with the meshing teeth is set to be opposite, and as a result, the axial movement of the internal and external gears is restricted.
[0041] また、本発明によれば、内外歯車の内歯の捩れ角は、 Θ であり、内外歯車の外周  [0041] Further, according to the present invention, the twist angle of the internal teeth of the internal and external gears is Θ, and the outer periphery of the internal and external gears
a  a
面嚙合歯の捩れ角は、 Θ であり、内外歯車の内歯の嚙合いピッチ円半径は、 rであ  The twist angle of the face meshing teeth is Θ, and the meshing pitch circle radius of the internal teeth of the internal and external gears is r.
b a り、内外歯車の外周面嚙合歯とベルトの嚙合歯との嚙合いピッチ円半径は、 rであり  b, the meshing pitch circle radius between the outer peripheral surface gear teeth of the inner and outer gears and the belt gear teeth is r.
b  b
(式 4) rh tan 9b (Equation 4) r h tan 9 b
τα tan τ α tan
に設定してある。 It is set to.
[0042] これにより、外歯車の外歯と内外歯車の内歯との嚙合いから発生する内外歯車を 軸方向移動させようとする力と、内外歯車の外周面嚙合歯とベルトの嚙合歯との嚙合 いから発生する内外歯車を軸方向移動させようとする力とを、等しくなるように設定し 、その結果、内外歯車の軸方向移動を規制している。  [0042] Accordingly, the force for axially moving the internal and external gears generated from the meshing of the external teeth of the external gear and the internal teeth of the internal and external gears, The force to move the inner and outer gears generated by the meshing in the axial direction is set to be equal, and as a result, the axial movement of the inner and outer gears is restricted.
[0043] 従って、内外歯車の軸方向移動を規制し、作動トルクの増加や耐久性の低下を抑 制すると共に、異音の発生を防止することができる。  [0043] Therefore, the axial movement of the internal and external gears can be restricted to suppress an increase in operating torque and a decrease in durability, and the generation of abnormal noise can be prevented.
図面の簡単な説明  Brief Description of Drawings
[0044] [図 1]本発明の実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電動パ ワーステアリング装置の縦断面図である。  FIG. 1 is a longitudinal sectional view of an electric power steering apparatus of a ball screw type and another-shaft rack assist type according to an embodiment of the present invention.
[図 2]図 1の A— A線 (一点鎖線側）に沿った断面図である。 [図 3]図 1の B— B線（二点鎖線側）に沿った断面図である。 FIG. 2 is a cross-sectional view along the line A—A (dashed line side) in FIG. FIG. 3 is a cross-sectional view taken along line BB (two-dot chain line side) in FIG.
圆 4]本発明の第 2実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電動 パワーステアリング装置の縦断面図である。 FIG. 4 is a longitudinal sectional view of a ball screw type separate-axis rack assist type electric power steering apparatus according to a second embodiment of the present invention.
圆 5]本発明の第 2実施の形態に係り、円形支持体と円環支持体との接触部を拡大し て示す拡大断面図である。 FIG. 5 is an enlarged cross-sectional view showing, in an enlarged manner, a contact portion between a circular support and an annular support according to a second embodiment of the present invention.
圆 6A]本発明の第 2実施の形態の変形例に係り、円形支持体と円環支持体との接触 部を拡大して示す拡大断面図である。 6A] An enlarged cross-sectional view showing a contact portion between a circular support and an annular support according to a modification of the second embodiment of the present invention.
圆 6B]本発明の第 2実施の形態の変形例に係り、円形支持体と円環支持体との接触 部を拡大して示す拡大断面図である FIG. 6B is an enlarged cross-sectional view showing, in an enlarged manner, a contact portion between the circular support and the annular support according to a modification of the second embodiment of the present invention.
圆 6C]本発明の第 2実施の形態の変形例に係り、円形支持体と円環支持体との接触 部を拡大して示す拡大断面図である FIG. 6C] is an enlarged cross-sectional view showing, in an enlarged manner, the contact portion between the circular support and the annular support according to a modification of the second embodiment of the present invention.
圆 7]本発明の第 3実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電動 パワーステアリング装置の要部の拡大断面図である。 FIG. 7 is an enlarged cross-sectional view of a main part of a ball screw type separate-shaft rack assist type electric power steering device according to a third embodiment of the present invention.
圆 8]本発明の第 4実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電動 パワーステアリング装置の縦断面図である。 FIG. 8 is a longitudinal sectional view of a ball screw type separate-axis rack assist type electric power steering device according to a fourth embodiment of the present invention.
圆 9]本発明の第 5実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電動 パワーステアリング装置の縦断面図である。 FIG. 9 is a longitudinal sectional view of a ball screw type separate-axis rack assist type electric power steering device according to a fifth embodiment of the present invention.
圆 10A]図 9に示した円形支持体と円環支持体の拡大断面図である。 FIG. 10A is an enlarged cross-sectional view of the circular support and the annular support shown in FIG.
圆 10B]本発明の第 6実施の形態に係り、円形支持体と円環支持体の拡大断面図で ある。 FIG. 10B] is an enlarged cross-sectional view of a circular support and an annular support according to a sixth embodiment of the present invention.
[図 10C]本発明の第 7実施の形態に係り、円形支持体と円環支持体の拡大断面図で ある。  FIG. 10C is an enlarged cross-sectional view of a circular support and an annular support according to a seventh embodiment of the present invention.
[図 11]本発明の実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電動パ ワーステアリング装置の縦断面図である。  FIG. 11 is a vertical cross-sectional view of a ball screw type separate-shaft rack assist type electric power steering apparatus according to an embodiment of the present invention.
[図 12A]図 11に示した、外歯車と、内外歯車と、ベルトとの嚙合い部を拡大して示す 模式図である。  FIG. 12A is a schematic diagram showing an enlarged view of a meshing portion of the external gear, the internal / external gear, and the belt shown in FIG. 11.
[図 12B]外歯車の外歯と内外歯車の内歯との嚙合いピッチ線 (X)を破線で示し、内 外歯車の外周面嚙合歯とベルトの嚙合歯との嚙合 ヽピッチ線を実線 (Y)で示した模 式図である。 [Fig. 12B] The meshing pitch line (X) between the external teeth of the external gear and the internal teeth of the internal and external gears is indicated by a broken line, and the meshing pitch line of the external surface meshing teeth of the internal and external gears and the meshing teeth of the belt (Y) FIG.
符号の説明 Explanation of symbols
1， 2, 3 ハ r  1, 2, 3 c
4 電動モータ  4 Electric motor
5 駆動軸  5 Drive shaft
7 枢軸  7 Axis
8, 9 軸受  8, 9 Bearing
11 小径の外歯車  11 Small diameter external gear
12 リング状の内外歯車  12 Ring-shaped inner and outer gears
12a 内歯  12a internal teeth
12b 外周面嚙合歯  12b Peripheral teeth
13 従動側プーリ  13 Driven pulley
14 ベルト  14 Belt
21 ラック軸  21 Rack shaft
22 ボー/レナット  22 baud / renut
23 雄ねじ溝  23 Male thread groove
24 雌ねじ溝  24 Female thread groove
25 鋼球  25 steel balls
26 複列軸受  26 Double row bearing
27 筒状体  27 Cylindrical body
28 スプライン咅  28 Spline 咅
31 円形支持体  31 Circular support
32 円環支持体  32 Toroidal support
40 フランジ  40 flange
41 斜歯ベルト  41 inclined belt
発明を実施するための最良の形態 BEST MODE FOR CARRYING OUT THE INVENTION
以下、本発明の実施の形態に係る電動パワーステアリング装置を図面を参照しつ つ説明する。 [0047] 図 1は、本発明の実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電 動パワーステアリング装置の縦断面図である。 Hereinafter, an electric power steering apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an electric power steering device of a ball screw type and a separate axis type rack assist type according to an embodiment of the present invention.
[0048] 図 2は、図 1の A— A線 (一点鎖線側）に沿った断面図である。 FIG. 2 is a cross-sectional view taken along the line AA (dotted line) in FIG.
[0049] 図 3は、図 1の B— B線（二点鎖線側）に沿った断面図である。 FIG. 3 is a cross-sectional view taken along the line BB (two-dot chain line side) in FIG.
[0050] 本実施の形態においては、図 1に示すように、ハウジング 1, 2, 3 (ステアリングギヤ ケース）が設けてあり、ノ、ウジング 1には、電動モータ 4が装着してある。 In the present embodiment, as shown in FIG. 1, housings 1, 2, 3 (steering gear cases) are provided, and an electric motor 4 is attached to the nosing and udging 1.
[0051] この電動モータ 4の駆動軸 5の凹端部には、枢軸 7がスプライン嵌合してある。この 枢軸 7は、ハウジング 1, 2に、軸受 8, 9により回転自在に支持してある。 [0051] The pivot shaft 7 is spline-fitted to the concave end portion of the drive shaft 5 of the electric motor 4. The pivot 7 is rotatably supported on the housings 1 and 2 by bearings 8 and 9.
[0052] 枢軸 7には、外歯を有する小径の外歯車 11が形成してある。図 2に示すように、そ の外歯車 11には、内歯を有するリング状の内外歯車 12が嚙合してある。この内外歯 車 12は、外歯車 11の軸線を中心に揺動可能に支持され、外周面が駆動側プーリと して作用するように構成してある（即ち、内外歯車 12の外周面には、後述するベルト[0052] A small-diameter external gear 11 having external teeth is formed on the pivot shaft 7. As shown in FIG. 2, a ring-shaped internal / external gear 12 having internal teeth is meshed with the external gear 11. The internal and external gears 12 are supported so as to be swingable about the axis of the external gear 11, and the outer peripheral surface acts as a driving pulley (that is, the outer peripheral surface of the internal and external gears 12 has , Belt to be described later
14に嚙合する嚙合歯が形成してある）。 14) is formed.
[0053] 内外歯車 12の外周面の嚙合歯と、後述するラック軸 21の同軸上に設けた従動側 プーリ 13の外周面の嚙合歯との間には、内側に嚙合歯を有するベルト 14が掛け渡 してある。 [0053] Between the meshing teeth on the outer peripheral surface of the internal / external gear 12 and the meshing teeth on the outer peripheral surface of the driven pulley 13 provided coaxially with the rack shaft 21 described later, a belt 14 having meshing teeth on the inside is provided. It's hanging over.
[0054] 一方、ハウジング 1, 2, 3 (ステアリングギヤケース）には、ラック軸 21が軸方向移動 自在に収納してあり、ラック軸 21には、ボールナット 22を備えたボールねじ機構が設 けてある。  [0054] On the other hand, in the housings 1, 2, 3 (steering gear case), a rack shaft 21 is accommodated so as to be movable in the axial direction, and the rack shaft 21 is provided with a ball screw mechanism including a ball nut 22. It is.
[0055] ラック軸 21には、雄ねじ溝 23が形成してある一方、ボールナット 22には、雌ねじ溝 24が形成してあり、雄ねじ溝 23と雌ねじ溝 24との間には、循環ボールたる多数個の 鋼球 25が介装してある。また、ボールナット 22には、鋼球 25を循環させるための循 環こま (図示せず)が装着してある。  The rack shaft 21 is formed with a male screw groove 23, while the ball nut 22 is formed with a female screw groove 24. A circular ball is formed between the male screw groove 23 and the female screw groove 24. A large number of steel balls 25 are interposed. The ball nut 22 is provided with a circulation top (not shown) for circulating the steel ball 25.
[0056] ボールナット 22は、複列軸受 26により支持してあり、その端部の筒状体 27に設け たスプライン部 28で、従動側プーリ 13がボールナット 22と共に回転できるように連結 してある。  [0056] The ball nut 22 is supported by a double row bearing 26, and is connected so that the driven pulley 13 can rotate together with the ball nut 22 at a spline portion 28 provided on the cylindrical body 27 at the end thereof. is there.
[0057] さて、本実施の形態では、図 1及び図 3に示すように、外歯車 11の両端部に、略同 軸上に、円形支持体 31が設けてあり、内外歯車 12の両端部に、略同軸上に、円形 支持体 31を内接して支持する円環支持体 32が設けてある。 In the present embodiment, as shown in FIGS. 1 and 3, circular support bodies 31 are provided on both ends of the outer gear 11 on substantially the same axis, and both ends of the inner and outer gears 12 are provided. A circle on the same axis An annular support 32 that supports the support 31 inwardly is provided.
[0058] そのため、内外歯車 12の外周面に作用する張力のうちのラジアル力は、円形支持 体 31と円環支持体 32とにより支持することができ、両歯車 11, 12は、トルク伝達のみ を受け持つことができる。 Therefore, the radial force of the tension acting on the outer peripheral surface of the internal / external gear 12 can be supported by the circular support 31 and the annular support 32, and both the gears 11 and 12 can transmit only torque. Can take charge.
[0059] 従って、両歯車 11, 12には、ベルトの張力によるラジアル力は、作用せず、内外歯 車 12が外歯車 11に食い込む事がない。よって、歯の耐久強度を向上し、作動音や 作動トルクを低減することができる。 Therefore, the radial force due to the belt tension does not act on the gears 11 and 12, and the inner and outer gears 12 do not bite into the outer gear 11. Therefore, the durability strength of the teeth can be improved and the operating noise and operating torque can be reduced.
[0060] また、円形支持体 31は、その外径が外歯車 11のピッチ円直径に略等しく設定して あり、円環支持体 32は、その内径が内外歯車 12の内歯のピッチ円直径に略等しく設 定してある。そのため、円形支持体 31と円環支持体 32の接触部は、滑りを伴う接触 ではなぐ転がり接触となるので、摩擦に伴う作動トルクの増加を最小限に抑えること ができる。  [0060] Further, the circular support 31 has an outer diameter set substantially equal to the pitch circle diameter of the outer gear 11, and the annular support 32 has an inner diameter of the pitch circle diameter of the inner teeth of the inner / outer gear 12. Is set approximately equal to. Therefore, the contact portion between the circular support 31 and the annular support 32 becomes a rolling contact rather than a contact with slipping, so that an increase in operating torque due to friction can be minimized.
[0061] なお、本発明は、上述した実施の形態に限定されず、種々変形可能である。  Note that the present invention is not limited to the above-described embodiment, and can be variously modified.
[0062] 上述した第 1の実施の形態では、内外歯車 12に、フランジが設けられておらず、ベ ルト 14が回転して軸方向に移動した場合には、従動側プーリ 13を支持する軸受ゃ ハウジング 1, 2などに、ベルト 14の側面が接触することが起こり得る。 In the first embodiment described above, the inner / outer gear 12 is not provided with a flange, and the bearing that supports the driven pulley 13 when the belt 14 rotates and moves in the axial direction. N Sides of the belt 14 may come into contact with the housings 1 and 2.
[0063] このような場合、この接触部の摩擦.磨耗による作動トルクの増加やベルトの耐久性 低下、滑り接触による異音発生などが問題となるといつたことがある。 [0063] In such a case, there have been occasions when an increase in operating torque due to friction and wear of the contact portion, a decrease in durability of the belt, generation of abnormal noise due to sliding contact, or the like becomes a problem.
そこで、この点を改良した実施の形態について以下に詳述する。  Therefore, an embodiment in which this point is improved will be described in detail below.
[0064] 上述した第 1の実施の形態に加え、円形支持体 31と円環支持体 32とが、内外歯車[0064] In addition to the first embodiment described above, the circular support 31 and the annular support 32 include an internal and external gear.
12の軸方向移動を規制する移動規制機構を有する実施の形態を第 2から第 4実施 の形態として詳述する。 Embodiments having a movement restricting mechanism that restricts twelve axial movements will be described in detail as second to fourth embodiments.
[0065] (第 2実施の形態） [0065] (Second Embodiment)
本実施の形態では、円形支持体 31と円環支持体 32は、内外歯車 12の軸方向移 動を規制する移動規制機構を有して 、る。  In the present embodiment, the circular support 31 and the annular support 32 have a movement restricting mechanism that restricts the axial movement of the inner and outer gears 12.
[0066] 図 4及び図 5に示すように、移動規制機構は、円形支持体 31の外周面が凹円弧形 状に形成してあり、円環支持体 32の内周面が凸円弧形状に形成してある。 As shown in FIGS. 4 and 5, in the movement restricting mechanism, the outer peripheral surface of the circular support 31 is formed in a concave arc shape, and the inner peripheral surface of the annular support 32 is a convex arc shape. Is formed.
[0067] ところで、電動モータ 4の駆動軸 5の回転によって、外歯車 11が回転し、その回転 は、内外歯車 12に伝達し、ベルト 14を介して、従動側プーリ 13に伝わる。 [0067] By the way, the external gear 11 is rotated by the rotation of the drive shaft 5 of the electric motor 4, and the rotation thereof. Is transmitted to the inner / outer gear 12 and is transmitted to the driven pulley 13 via the belt 14.
[0068] この時、ベルト 14は、その芯線の向きや傾き、ベルト 14自身の捩れなどによって、 ベルト 14は、軸方向に移動しょうとする。 [0068] At this time, the belt 14 tends to move in the axial direction due to the orientation and inclination of the core wire, the twist of the belt 14 itself, and the like.
[0069] また、内外歯車 12も、ベルト 14の回転力によって軸方向に移動しょうとする。 [0069] Further, the internal / external gear 12 also attempts to move in the axial direction by the rotational force of the belt 14.
[0070] 本実施の形態では、円形支持体 31の外周面が凹円弧形状に形成してあり、円環 支持体 32の内周面が凸円弧形状に形成してあり、また、内外歯車 12は、常に、従動 側プーリ 13方向にベルトの張力よつて押し付けられている。 In the present embodiment, the outer peripheral surface of the circular support 31 is formed in a concave arc shape, the inner peripheral surface of the annular support 32 is formed in a convex arc shape, and the internal / external gear 12 Is always pressed in the direction of the driven pulley 13 by the belt tension.
[0071] その結果、凹凸円弧形状が案内の役割を果たし、内外歯車 12の軸方向移動を規 制することができ、内外歯車 12とハウジング 1, 2等との接触を回避することができる。 As a result, the concavo-convex arc shape plays a role of guiding, and the axial movement of the internal / external gear 12 can be restricted, and the contact between the internal / external gear 12 and the housings 1, 2, etc. can be avoided.
[0072] 従って、滑り接触による作動トルクの増加や耐久性の低下を抑制すると共に、異音 の発生を防止することができる。 [0072] Therefore, it is possible to suppress an increase in operating torque and a decrease in durability due to sliding contact, and to prevent generation of abnormal noise.
[0073] し力も、凹凸形状は、例えば、それぞれ異なる曲率半径として、円形支持体 31と円 環支持体 32との接触部を略点接触に近い接触形態としている。これにより、接触部 が小面積 (略点接触)で転がり接触することにより、摩擦'摩耗を著しく低減することが できる。 [0073] The concavo-convex shape has, for example, different contact radii, and the contact portion between the circular support 31 and the annular support 32 has a contact form close to point contact. Thus, the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
[0074] また、円形支持体 31と円環支持体 32の凹凸形状は、内外歯車 12の軸方向移動を 規制できれば良い。図 6Aのように、円形支持体 31と円環支持体 32の凹凸形状は、 曲面でなくともよぐ凹凸形状であって、略鈍角形状で接触するように形成してあって ちょい。  [0074] The uneven shape of the circular support 31 and the annular support 32 only needs to be able to regulate the axial movement of the internal / external gear 12. As shown in FIG. 6A, the concavo-convex shape of the circular support 31 and the annular support 32 is not necessarily a curved surface, but may be formed so as to be in contact with a substantially obtuse angle.
[0075] また、図 6Bのように、円形支持体 31と円環支持体 32で、凹凸円弧形状の向きが逆 であっても良い。  [0075] Further, as shown in FIG. 6B, the circular support 31 and the annular support 32 may have the directions of the concave and convex arc shapes reversed.
[0076] さらに、図 6Cに示すように、凹凸円弧形状での接触部を複数箇所としても良い。  [0076] Furthermore, as shown in FIG. 6C, a plurality of contact portions in an uneven arc shape may be provided.
[0077] (第 3実施の形態） [0077] (Third embodiment)
図 7は、本発明の第 3実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の 電動パワーステアリング装置の要部の拡大断面図である。  FIG. 7 is an enlarged cross-sectional view of a main part of a ball screw type, separate-axis rack assist type electric power steering apparatus according to a third embodiment of the present invention.
[0078] 本実施の形態は、その基本的構造が上述した実施の形態と同様であり、相違する 点について説明する。 This embodiment is the same as the above-described embodiment in the basic structure, and the differences will be described.
[0079] 本実施の形態では、円形支持体 31と円環支持体 32は、内外歯車 12の軸方向移 動を規制する移動規制機構を有して 、る。 In the present embodiment, the circular support 31 and the annular support 32 are arranged so that the internal and external gears 12 move in the axial direction. It has a movement regulation mechanism that regulates movement.
[0080] 図 7に示すように、移動規制機構は、円形支持体 31と円環支持体 32との接触部の 形状がテーパ形状として対向してあり、且つ、対称に形成してある。  As shown in FIG. 7, in the movement restricting mechanism, the contact portions of the circular support 31 and the annular support 32 are opposed to each other as a tapered shape, and are formed symmetrically.
[0081] ところで、内外歯車 12がベルト 14の回転力によって軸方向に移動しょうとする際、 本実施の形態では、円形支持体 31と円環支持体 32との接触部の形状がテーパ形 状として対向してあり、且つ、対称に形成してあり、また、内外歯車 12は、常に、従動 側プーリ 13方向に張力よつて押し付けられて 、る。 By the way, when the internal / external gear 12 is about to move in the axial direction by the rotational force of the belt 14, in the present embodiment, the shape of the contact portion between the circular support 31 and the annular support 32 is tapered. The internal and external gears 12 are always pressed against the driven pulley 13 by tension.
[0082] その結果、このようなテーパであって対称的な形状が案内の役割を果たし、内外歯 車 12の軸方向移動を規制することができ、内外歯車 12とハウジング 1, 2等との接触 を回避することができる。 [0082] As a result, such a tapered and symmetric shape serves as a guide, and the axial movement of the inner and outer gears 12 can be restricted. Contact can be avoided.
[0083] 従って、滑り接触による作動トルクの増加や耐久性の低下を抑制すると共に、異音 の発生を防止することができる。 [0083] Accordingly, it is possible to suppress an increase in operating torque and a decrease in durability due to sliding contact, and to prevent generation of abnormal noise.
[0084] し力も、テーパであって対称的な形状であることから、円形支持体 31と円環支持体[0084] Since the compressive force is also tapered and symmetrical, the circular support 31 and the annular support
32との接触部を略点接触に近い接触形態としている。これにより、接触部が小面積（ 略点接触)で転がり接触することにより、摩擦'摩耗を著しく低減することができる。 The contact portion with 32 is in a contact form that is close to point contact. Accordingly, the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
[0085] なお、テーパの向きは、円形支持体 31と円環支持体 32とで、逆になつていても良 い。 Note that the direction of the taper may be reversed between the circular support 31 and the annular support 32.
[0086] (第 4実施の形態）  [0086] (Fourth embodiment)
図 8は、本発明の第 4実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の 電動パワーステアリング装置の縦断面図である。  FIG. 8 is a longitudinal sectional view of a ball screw type, separate-axis rack assist type electric power steering apparatus according to a fourth embodiment of the present invention.
[0087] 本実施の形態は、その基本的構造が上述した実施の形態と同様であり、相違する 点について説明する。 [0087] The present embodiment is the same in basic structure as the above-described embodiment, and differences will be described.
[0088] 本実施の形態では、内外歯車 12の外周面の嚙合歯と、後述するラック軸 21の同軸 上に設けた従動側プーリ 13の外周面の嚙合歯との間には、内側に嚙合歯を有する 斜歯ベルト 41が掛け渡してある。  In the present embodiment, the meshing teeth on the outer peripheral surface of the internal / external gear 12 and the meshing teeth on the outer peripheral surface of the driven pulley 13 provided coaxially with the rack shaft 21 described later are meshed inward. An inclined belt 41 having teeth is stretched over.
[0089] 内外歯車 12の回転が斜歯ベルト 41を介して従動側プーリ 13に伝わる時、斜歯べ ルト 41は、斜歯の角度、芯線の向きや傾き、斜歯ベルト 41自身の捩れなどによって、 軸方向に移動しょうとする。 [0090] 本実施の形態においても、斜歯ベルト 41が軸方向に移動しょうとする際、円形支持 体 31の外周面が凹円弧形状に形成してあり、円環支持体 32の外周面が凸円弧形 状に形成してあり、また、内外歯車 12は、常に、従動側プーリ 13方向にベルトの張力 によって押し付けられて 、る。 [0089] When the rotation of the internal / external gear 12 is transmitted to the driven pulley 13 via the inclined tooth belt 41, the inclined tooth belt 41 has the inclined tooth angle, the direction and inclination of the core wire, the twist of the inclined tooth belt 41 itself, etc. Tries to move in the axial direction. Also in the present embodiment, when the inclined belt 41 tries to move in the axial direction, the outer peripheral surface of the circular support 31 is formed in a concave arc shape, and the outer peripheral surface of the annular support 32 is The inner and outer gears 12 are always pressed in the direction of the driven pulley 13 by the belt tension.
[0091] その結果、凹凸円弧形状が案内の役割を果たし、内外歯車 12の軸方向移動を規 制することができ、内外歯車 12とハウジング 1, 2等との接触を回避することができる。  As a result, the concavo-convex arc shape plays a role of guiding, the axial movement of the internal / external gear 12 can be restricted, and the contact between the internal / external gear 12 and the housings 1, 2, etc. can be avoided.
[0092] 従って、内外歯車が移動せず、他と接触を起こさな 、ので、作動トルク低減と異音 発生防止が期待できる。従って、作動トルク低減の結果として歯の耐久強度の向上 が期待できる。換言すれば、滑り接触による作動トルクの増加や耐久性の低下を抑 制すると共に、異音の発生を防止することが期待できる。  [0092] Accordingly, since the internal and external gears do not move and do not come into contact with others, it is possible to reduce the operating torque and prevent the generation of abnormal noise. Therefore, improvement of the endurance strength of the teeth can be expected as a result of the reduction of the operating torque. In other words, it can be expected to suppress an increase in operating torque and a decrease in durability due to sliding contact and to prevent the generation of abnormal noise.
[0093] し力も、凹凸形状は、例えば、それぞれ異なる曲率半径として、円形支持体 31と円 環支持体 32と接触部を略点接触に近い接触形態としている。これにより、接触部が 小面積 (略点接触)で転がり接触することにより、摩擦'摩耗を著しく低減することがで きる。  [0141] The concave and convex shapes of the concave and convex shapes are, for example, different contact radii, and the contact portions of the circular support 31 and the annular support 32 and the contact portions are substantially close to point contact. As a result, the frictional wear can be significantly reduced by the rolling contact of the contact portion with a small area (substantially point contact).
[0094] なお、本発明は、上述した実施の形態に限定されず、種々変形可能である。  Note that the present invention is not limited to the above-described embodiment, and can be variously modified.
[0095] 次に第 5から第 7の実施の形態として、上述の第 1実施の形態に加え、内外歯車の 両側部に、ベルトの軸方向移動を規制するためのフランジを設けた形態にっ 、て説 明する。 [0095] Next, as fifth to seventh embodiments, in addition to the first embodiment described above, flanges for restricting axial movement of the belt are provided on both sides of the internal and external gears. I will explain.
[0096] (第 5実施の形態） [0096] (Fifth embodiment)
上述の第 1実施の形態に加え、図 10Aに示すように、内外歯車 12の両側部に、ベ ルト 14の軸方向移動を規制するためのフランジ 40が設けた実施の形態について、 第 5から第 7の実施の形態として説明する。  In addition to the first embodiment described above, as shown in FIG. 10A, an embodiment in which flanges 40 for restricting the axial movement of the belt 14 are provided on both sides of the inner and outer gears 12 will be described. This will be described as a seventh embodiment.
[0097] ところで、電動モータ 4の駆動軸 5の回転によって、外歯車 11が回転し、その回転 は、内外歯車 12に伝達し、ベルト 14を介して、従動側プーリ 13に伝わる。この時、ベ ルト 14は、その芯線の向きや傾き、ベルト 14自身の捩れなどによって、ベルト 14は、 軸方向に移動しょうとする。また、ベルト 14が斜歯ベルト（図示略)ならば、斜歯の角 度によっても、軸方向へ移動する。 By the way, the external gear 11 is rotated by the rotation of the drive shaft 5 of the electric motor 4, and the rotation is transmitted to the internal / external gear 12 and is transmitted to the driven pulley 13 via the belt 14. At this time, the belt 14 tries to move in the axial direction due to the orientation and inclination of the core wire and the twist of the belt 14 itself. If the belt 14 is an inclined belt (not shown), the belt 14 moves in the axial direction depending on the angle of the inclined teeth.
[0098] このような場合、本実施の形態では、上記のように、内外歯車 12の両側部に、ベル ト 14の軸方向移動を規制するためのフランジ 40が設けてある。 In such a case, in the present embodiment, as described above, the bell A flange 40 is provided to restrict the axial movement of the G14.
[0099] 従って、ベルト 14が軸方向移動してハウジング 1, 2などに接触することを回避する ことができ、それによる作動トルクの増カロ、耐久性の低下、異音の発生を確実に防止 することができる。 [0099] Therefore, it is possible to avoid the belt 14 from moving in the axial direction and coming into contact with the housings 1, 2, etc., thereby reliably preventing increase in operating torque, deterioration in durability, and generation of abnormal noise. can do.
[0100] (第 6実施の形態） [0100] (Sixth embodiment)
図 10Bは、本発明の第 6実施の形態に係り、円形支持体と円環支持体の拡大断面 図である。  FIG. 10B is an enlarged cross-sectional view of a circular support and an annular support according to the sixth embodiment of the present invention.
[0101] 本実施の形態では、フランジ 40は、内外歯車 12の端部に設けた円環支持体 32に 一体的に形成してある。  In the present embodiment, the flange 40 is formed integrally with the annular support 32 provided at the end of the internal / external gear 12.
[0102] 従って、この場合にも、ベルト 14が軸方向移動してハウジング 1, 2などに接触する ことを回避することができ、それによる作動トルクの増カロ、耐久性の低下、異音の発生 を確実に防止することができる。 [0102] Therefore, in this case as well, it is possible to avoid the belt 14 from moving in the axial direction and coming into contact with the housings 1, 2, etc., thereby increasing the operating torque, reducing the durability, and generating abnormal noise. Occurrence can be reliably prevented.
[0103] カロえて、フランジ 40は、円環支持体 32に一体的に形成してあることから、フランジを 別体で取付けるための手段の省略、取付け部の肉厚の低減が可能であり、構造をコ ンパタトにする効果を有する。 [0103] Since the flange 40 is formed integrally with the annular support 32, the means for attaching the flange separately can be omitted, and the thickness of the attachment portion can be reduced. It has the effect of making the structure compact.
[0104] (第 7実施の形態） [Seventh Embodiment]
図 10Cは、本発明の第 7実施の形態に係り、円形支持体と円環支持体の拡大断面 図である。  FIG. 10C is an enlarged cross-sectional view of a circular support and an annular support according to the seventh embodiment of the present invention.
[0105] 本実施の形態では、フランジ 40は、内外歯車 12の端部に設けた円環支持体 32に 一体的に形成してある。  In the present embodiment, the flange 40 is formed integrally with the annular support 32 provided at the end of the internal / external gear 12.
[0106] 従って、この場合にも、ベルト 14が軸方向移動してハウジング 1, 2などに接触する ことを回避することができ、それによる作動トルクの増カロ、耐久性の低下、異音の発生 を確実に防止することができる。 [0106] Therefore, in this case as well, it is possible to avoid the belt 14 from moving in the axial direction and coming into contact with the housings 1, 2, etc., thereby increasing the operating torque, reducing the durability, and generating abnormal noise. Occurrence can be reliably prevented.
[0107] カロえて、フランジ 40は、円環支持体 32に一体的に形成してあることから、フランジを 別体で取付けるための手段の省略、取付け部の肉厚の低減が可能であり、構造をコ ンパタトにする効果を有する。 [0107] Since the flange 40 is formed integrally with the annular support body 32, means for attaching the flange separately can be omitted, and the thickness of the attachment portion can be reduced. It has the effect of making the structure compact.
[0108] また、本実施の形態では、円形支持体 31と円環支持体 32は、内外歯車 12の軸方 向移動を規制する移動規制機構を有している。移動規制機構は、円形支持体 31の 外周面が凹円弧形状に形成してあり、円環支持体 32の内周面が凸円弧形状に形成 してある。 In the present embodiment, the circular support 31 and the annular support 32 have a movement restricting mechanism that restricts the axial movement of the internal / external gear 12. The movement restricting mechanism is The outer peripheral surface is formed in a concave arc shape, and the inner peripheral surface of the annular support body 32 is formed in a convex arc shape.
[0109] 円形支持体 31の外周面が凹円弧形状に形成してあり、円環支持体 32の内周面が 凸円弧形状に形成してあり、また、内外歯車 12は、常に、従動側プーリ 13方向にベ ルトの張力によって押し付けられている。その結果、凹凸円弧形状が案内の役割を 果たし、内外歯車 12の軸方向移動を規制することができ、内外歯車 12とハウジング 1, 2等との接触を回避することができる。従って、滑り接触による作動トルクの増加や 耐久性の低下を抑制すると共に、異音の発生を防止することができる。  [0109] The outer peripheral surface of the circular support 31 is formed in a concave arc shape, the inner peripheral surface of the annular support 32 is formed in a convex arc shape, and the inner / outer gear 12 is always driven side It is pressed against the pulley 13 by the belt tension. As a result, the concavo-convex arc shape serves as a guide, and the axial movement of the inner / outer gear 12 can be restricted, and contact between the inner / outer gear 12 and the housings 1, 2, etc. can be avoided. Accordingly, an increase in operating torque and a decrease in durability due to sliding contact can be suppressed, and abnormal noise can be prevented.
[0110] し力も、凹凸形状は、例えば、それぞれ異なる曲率半径として、円形支持体 31と円 環支持体 32との接触部を略点接触に近い接触形態としている。これにより、接触部 が小面積 (略点接触)で転がり接触することにより、摩擦'摩耗を著しく低減することが できる。  [0110] The concavo-convex shape has, for example, different radii of curvature, and the contact portion between the circular support 31 and the annular support 32 has a contact form close to point contact. Thus, the frictional wear can be remarkably reduced by the rolling contact of the contact portion with a small area (substantially point contact).
[0111] また、円形支持体 31と円環支持体 32の凹凸形状は、内外歯車 12の軸方向移動を 規制できれば良い。円形支持体 31と円環支持体 32の凹凸形状は、曲面でなくともよ ぐ凹凸形状であって、略鈍角形状で接触するように形成してあってもよい。また、円 形支持体 31と円環支持体 32で、凹凸円弧形状の向きが逆であっても良い。さらに、 凹凸円弧形状での接触部を複数箇所としても良！ヽ。  [0111] The uneven shape of the circular support 31 and the annular support 32 only needs to be able to restrict the axial movement of the internal / external gear 12. The concavo-convex shape of the circular support 31 and the annular support 32 may be a concavo-convex shape that is not a curved surface, and may be formed so as to be in contact with a substantially obtuse angle. In addition, the circular support 31 and the circular support 32 may have reverse concave and convex arc shapes. In addition, it is also possible to have multiple contact points in an uneven arc shape!ヽ.
[0112] なお、本発明は、上述した実施の形態に限定されず、種々変形可能である。 Note that the present invention is not limited to the above-described embodiment, and various modifications can be made.
[0113] 上記の実施の形態 1〜7における外歯車の外歯、内外歯車の内歯及び外周面嚙 合歯、ベルトの嚙合歯、及び従動側プーリの外周面嚙合歯の歯の形状は、第 1〜3 実施例では直歯を用いた例を説明したが、これを第 4実施例のように斜歯を用いても 良い。（第 8実施の形態） [0113] The external teeth of the external gear, the internal teeth of the internal and external gears and the outer peripheral surface of the external teeth in the above-described first to seventh embodiments, the toothed teeth of the belt, and the teeth of the outer peripheral surface of the driven pulley are: In the first to third embodiments, examples using straight teeth have been described, but inclined teeth may be used as in the fourth embodiment. (Eighth embodiment)
しかし、以下に説明する本発明の第 8の実施の形態ではそれらの歯を斜歯に設定 し、斜歯の捩れ方向はいずれも同一方向に設定した。以下にその実施の形態を詳述 する。  However, in the eighth embodiment of the present invention described below, those teeth are set as oblique teeth, and the twisting directions of the inclined teeth are set in the same direction. The embodiment will be described in detail below.
[0114] 図 11は、本発明の実施の形態に係り、ボールねじ式で別軸式ラックアシスト型の電 動パワーステアリング装置の縦断面図である。  FIG. 11 is a longitudinal sectional view of an electric power steering device of a ball screw type and another-shaft type rack assist type according to an embodiment of the present invention.
[0115] 図 12Aは、図 11に示した、外歯車と、内外歯車と、ベルトとの嚙合い部を拡大して 示す模式図であり、図 12Bは、外歯車の外歯と内外歯車の内歯との嚙合いピッチ線 (X)を破線で示し、内外歯車の外周面嚙合歯とベルトの嚙合歯との嚙合いピッチ線 を実線 (Y)で示した模式図である。 [0115] FIG. 12A is an enlarged view of the meshing portion of the external gear, the internal / external gear, and the belt shown in FIG. FIG. 12B shows a meshing pitch line (X) between the external teeth of the external gear and the internal teeth of the internal / external gear by a broken line, and FIG. FIG. 5 is a schematic diagram showing the mating pitch line as a solid line (Y).
[0116] 本実施の形態では、図 12A、 12Bに示すように、外歯車 11の外歯、内外歯車 12の 内歯 12a及び外周面嚙合歯 12b、ベルト 14の嚙合歯、及び従動側プーリ 13の外周 面嚙合歯は、斜歯に設定してあり、これらの斜歯の捩れ方向は、同一方向になるよう に設定してある。 In this embodiment, as shown in FIGS. 12A and 12B, the external teeth of the external gear 11, the internal teeth 12a and the outer peripheral surface meshing teeth 12b of the internal and external gear 12, the meshing teeth of the belt 14, and the driven pulley 13 The peripheral teeth of the outer teeth are set to be inclined teeth, and the torsional directions of these inclined teeth are set to be the same direction.
[0117] 図 12Aに示すように、外歯車 11の外歯と内外歯車 12の内歯 12aとの嚙合いから、 内外歯車 12には、接線力（Fa)が発生する。  As shown in FIG. 12A, a tangential force (Fa) is generated in the internal / external gear 12 due to the meshing between the external teeth of the external gear 11 and the internal teeth 12a of the internal / external gear 12.
[0118] また、内外歯車 12の外周面嚙合歯 12bとベルト 14の嚙合歯との嚙合いから、内外 歯車 12には、接線力（Fb)が発生する。 [0118] Furthermore, a tangential force (Fb) is generated in the inner / outer gear 12 due to the engagement between the outer peripheral surface meshing teeth 12b of the inner / outer gear 12 and the meshing teeth of the belt 14.
[0119] これら接線力（Fa, Fb)から、斜歯の角度によって、図 12Bに示すような軸方向への 分力が発生し、内外歯車 12の軸線に水平な分力は、内外歯車 12の軸方向移動力と なる。 [0119] From these tangential forces (Fa, Fb), a component force in the axial direction as shown in Fig. 12B is generated depending on the angle of the inclined tooth, and the component force horizontal to the axis of the inner / outer gear 12 is the inner / outer gear 12 This is the axial movement force.
[0120] この時、上述した斜歯の捩れ方向が同一方向になるように設定してあれば、外歯車 11の外歯と内外歯車 12の内歯 12aとの嚙合いにより発生する軸方向移動力と、内 外歯車 12の外周面嚙合歯 12bとベルト 14の嚙合歯との嚙合いにより発生する軸方 向移動力とは、反対方向に働く。  [0120] At this time, if the twisting direction of the oblique teeth described above is set to be the same direction, the axial movement caused by the meshing between the external teeth of the external gear 11 and the internal teeth 12a of the internal / external gear 12 The force and the axial movement force generated by the engagement between the outer peripheral surface meshing teeth 12b of the internal and external gears 12 and the meshing teeth of the belt 14 work in opposite directions.
[0121] これにより、回転によって、外歯車 11の外歯と内外歯車 12の内歯 12aとの嚙合い から発生する内外歯車 12を軸方向移動させようとする軸方向移動力と、内外歯車 12 の外周面嚙合歯 12bとベルト 14の嚙合歯との嚙合いから発生する内外歯車 12を軸 方向移動させようとする軸方向移動力とを、互いに逆向きとなるように設定することが でき、その結果、内外歯車 12の軸方向移動を規制することができる。  [0121] Thus, by the rotation, the axial direction moving force for axially moving the internal / external gear 12 generated from the meshing between the external teeth of the external gear 11 and the internal teeth 12a of the internal / external gear 12, and the internal / external gear 12 The axial movement force for axially moving the internal / external gear 12 generated by the meshing of the outer peripheral surface meshing teeth 12b of the belt 14 and the meshing teeth of the belt 14 can be set to be opposite to each other. As a result, the axial movement of the inner / outer gear 12 can be restricted.
[0122] また、内外歯車 12の内歯 12aの捩れ角は、 Θ であり、内外歯車 12の外周面嚙合  [0122] Further, the twist angle of the internal teeth 12a of the internal / external gear 12 is Θ, and the outer peripheral surface of the internal / external gear 12 is meshed.
a  a
歯 12bの捩れ角は、 Θ であるとき、上記 2つの軸方向移動力が互いに反対方向であ  When the torsion angle of the tooth 12b is Θ, the two axial movement forces are opposite to each other.
b  b
つて、且つ、釣り合うためには、  In order to balance,
式 1  Formula 1
[0123]
Figure imgf000020_0001
となればよい。図 12Aにおいて、内外歯車 12の内歯 12aの嚙合いピッチ円半径は、 r であり、内外歯車 12の外周面嚙合歯 12bとベルト 14の嚙合歯との嚙合!、ピッチ円 a [0123]
Figure imgf000020_0001
If it becomes. In FIG. 12A, the meshing pitch circle radius of the internal teeth 12a of the internal / external gear 12 is r, the meshing teeth 12b of the outer peripheral surface 12 of the internal / external gear 12 and the meshing teeth of the belt 14 !, pitch circle a
半径は、 rであるとすると、接線力（Fa, Fb)は、夫々、嚙合い部に働くトルク力も求め  Assuming that the radius is r, the tangential force (Fa, Fb) is also the torque force acting on the mating part, respectively.
b  b
られ、  And
式 2  Formula 2
[0124]  [0124]
Figure imgf000020_0002
となり、式（1)は、
Figure imgf000020_0002
Equation (1) becomes
式 3  Formula 3
[0125]  [0125]
Figure imgf000020_0003
となる。ここで、内外歯車 12の内歯 12aと、外周面嚙合歯とは、当然、一体であり、伝 達するトルクは等しいから、
Figure imgf000020_0003
It becomes. Here, the internal teeth 12a of the internal / external gear 12 and the outer peripheral surface meshing teeth are of course integral and the transmitted torque is equal.
Ta=Tb  Ta = Tb
より、以下の式が算出される。  Thus, the following formula is calculated.
式 4 [0126] Equation 4 [0126]
rh tan Θ, r h tan Θ,
ra tan ^ r a tan ^
[0127] このため、以上の関係を持つ捩れ角を有する本実施の形態によれば、内外歯車 12 の内歯 12aと、外周面嚙合歯とに発生する 2つの軸方向移動力を、相殺することがで き、内外歯車 12の軸方向の移動を規制することができる。 [0127] Therefore, according to the present embodiment having a twist angle having the above relationship, the two axial movement forces generated in the internal teeth 12a of the internal / external gear 12 and the outer peripheral surface meshing teeth are canceled out. The axial movement of the internal / external gear 12 can be restricted.
[0128] 従って、内外歯車 12の軸方向移動を規制し、作動トルクの増加や耐久性の低下を 抑制すると共に、異音の発生を防止することができる。 Accordingly, the axial movement of the internal / external gear 12 can be restricted, and an increase in operating torque and a decrease in durability can be suppressed, and the occurrence of abnormal noise can be prevented.
[0129] なお、本発明は、上述した実施の形態に限定されず、種々変形可能である。 [0129] The present invention is not limited to the above-described embodiments, and various modifications can be made.
[0130] なお、上述の電動パワーステアリング装置は、通常の操舵機構のように前輪を操舵 するために用いてもょ 、し、 4輪操舵機構の前輪または後輪の操舵に用いることがで きることは当然である。 [0130] The electric power steering device described above may be used to steer the front wheels like a normal steering mechanism, and may be used to steer front wheels or rear wheels of a four-wheel steering mechanism. It is natural.
また、本発明は、ステアリングホイールとラック軸が機械的に連結されていない、い わゆるステアバイワイヤ（SBW)式のステアリングにも適用できる。 また、上述した第 The present invention can also be applied to a so-called steer-by-wire (SBW) type steering in which the steering wheel and the rack shaft are not mechanically connected. In addition, the above mentioned
1から第 8の実施の形態を組み合わせることも当然本発明に含まれる。 Of course, the present invention also includes a combination of the first to eighth embodiments.
本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲 を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明ら かである。  Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
本出願は、 2004年 12月 28日出願の日本特許出願（特願 2004— 381681)、 2005年 1 月 25日出願の日本特許出願 (特願 2005— 017257)、 2005年 1月 28日出願の日本特 許出願（特願 2005— 022075)、 2005年 3月 22日出願の日本特許出願（特願 2005— 08 2230)、に基づくものであり、その内容はここに参照として取り込まれる。  This application includes Japanese patent applications filed on December 28, 2004 (Japanese Patent Application No. 2004-381681), Japanese patent applications filed on January 25, 2005 (Japanese Patent Application No. 2005-017257), and Japanese patent applications filed on January 28, 2005. This is based on the Japanese patent application (Japanese Patent Application 2005-020275) and the Japanese patent application filed on March 22, 2005 (Japanese Patent Application 2005-02082230), the contents of which are incorporated herein by reference.
産業上の利用可能性  Industrial applicability
[0131] 上述した本発明によれば、内外歯車に作用するベルト張力のうちのラジアル力を、 円形支持体と円環支持体とにより支持することができ、両歯車はトルク伝達のみを受 け持つことができる。 従って、両歯車には、ベルト張力によるラジアル力は、作用せず、内外歯車が外歯 車に食い込む事がない。よって、歯の耐久強度が高ぐ作動音や作動トルクを低減す ることができる電動パワーステアリング装置が提供される。 [0131] According to the present invention described above, the radial force of the belt tension acting on the internal and external gears can be supported by the circular support and the annular support, and both gears receive only torque transmission. Can have. Therefore, the radial force due to the belt tension does not act on both gears, and the internal and external gears do not bite into the external gear. Therefore, an electric power steering apparatus that can reduce the operation noise and the operation torque with high tooth durability is provided.

Claims

請求の範囲 The scope of the claims
ステアリングホイールに印加した操舵トルクに対応して、電動モータから補助操舵ト ルクを発生させ、動力伝達機構を介して、操舵機構のラック軸に前記補助操舵トルク を伝達する別軸式ラックアシスト型の電動パワーステアリング装置において、 前記動力伝達機構は、  In response to the steering torque applied to the steering wheel, an auxiliary steering torque is generated from the electric motor, and the auxiliary steering torque is transmitted to the rack shaft of the steering mechanism via the power transmission mechanism. In the electric power steering apparatus, the power transmission mechanism is
前記電動モータにより駆動され、外歯を有する小径の外歯車と、  A small-diameter external gear driven by the electric motor and having external teeth;
当該外歯車に内接して嚙合する内歯を有し、当該外歯車の軸線を中心に揺動可 能に支持され、外周面が駆動側プーリとして作用するリング状の内外歯車と、 当該内外歯車により、ベルトを介して駆動される従動側プーリと、  A ring-shaped internal / external gear having internal teeth that are inscribed in mesh with the external gear, supported so as to be swingable about the axis of the external gear, and having an outer peripheral surface acting as a driving pulley, and the internal / external gear A driven pulley driven via a belt,
当該従動側プーリにより駆動されて、ラック軸を移動させるボールねじ機構と、を備 え、  A ball screw mechanism that is driven by the driven pulley and moves the rack shaft,
前記外歯車の端部に、略同軸上に、円形支持体が設けてあり、  At the end of the external gear, a circular support is provided substantially coaxially,
前記内外歯車の端部に、略同軸上に、前記円形支持体と内接して前記円形支持 体を支持する円環支持体が設けてあることを特徴とする電動パワーステアリング装置  An electric power steering apparatus characterized in that an annular support for supporting the circular support is provided at the end of the internal and external gears substantially coaxially and inscribed with the circular support.
[2] 前記円形支持体は、その外径が前記外歯車の内歯のピッチ円直径に略等しく設定 してあり、 [2] The outer diameter of the circular support is set substantially equal to the pitch circle diameter of the inner teeth of the external gear,
前記円環支持体は、その内径が前記内外歯車の内歯のピッチ円直径に略等しく設 定してあることを特徴とする請求項 1に記載の電動パワーステアリング装置。  2. The electric power steering apparatus according to claim 1, wherein an inner diameter of the annular support is set substantially equal to a pitch circle diameter of internal teeth of the internal and external gears.
[3] 前記円形支持体と前記円環支持体とは、前記内外歯車の軸方向移動を規制する 移動規制機構を有することを特徴とする請求項 1に記載の電動パワーステアリング装 置。  [3] The electric power steering device according to [1], wherein the circular support and the annular support have a movement restricting mechanism that restricts the axial movement of the internal and external gears.
[4] 前記円形支持体は、その外径が前記外歯車のピッチ円直径に略等しく設定してあ り、  [4] The outer diameter of the circular support is set to be approximately equal to the pitch circle diameter of the external gear,
前記円環支持体は、その内径が前記内外歯車の内歯のピッチ円直径に略等しく設 定してあることを特徴とする請求項 3に記載の電動パワーステアリング装置。  4. The electric power steering apparatus according to claim 3, wherein an inner diameter of the annular support is set substantially equal to a pitch circle diameter of internal teeth of the internal and external gears.
[5] 前記移動規制機構は、前記円形支持体と前記円環支持体との接触部の形状を、 一方を凸形状に形成し、他方を凹形状に形成してあることを特徴とする請求項 3に記 載の電動パワーステアリング装置。 [5] The movement restricting mechanism is characterized in that one of the contact portions between the circular support and the annular support is formed in a convex shape and the other is formed in a concave shape. Item 3 The electric power steering device.
[6] 前記移動規制機構は、前記円形支持体と前記円環支持体との接触部の形状を、 テーパ形状として対向し、且つ、対称に形成してあることを特徴とする請求項 3に記 載の電動パワーステアリング装置。  6. The movement restricting mechanism according to claim 3, wherein a shape of a contact portion between the circular support body and the annular support body is opposed and formed symmetrically as a tapered shape. The electric power steering apparatus described.
[7] 前記内外歯車の側部に、フランジが設けてあることを特徴とする請求項 1に記載の 電動パワーステアリング装置。 7. The electric power steering apparatus according to claim 1, wherein a flange is provided on a side portion of the internal / external gear.
[8] 前記フランジは、前記内外歯車の端部に設けた前記円環支持体に一体的に形成 してあることを特徴とする請求項 7に記載の電動パワーステアリング装置。 8. The electric power steering apparatus according to claim 7, wherein the flange is formed integrally with the annular support provided at an end of the internal / external gear.
[9] 前記外歯車の外歯、前記内外歯車の内歯及び外周面嚙合歯、前記ベルトの嚙合 歯、及び前記従動側プーリの外周面嚙合歯は、斜歯に設定してあり、 [9] The external teeth of the external gear, the internal teeth and outer peripheral surface meshing teeth of the internal / external gear, the meshing teeth of the belt, and the external surface meshing teeth of the driven pulley are set to bevel teeth,
これらの斜歯の捩れ方向は、同一方向になるように設定してあることを特徴とする請 求項 1に記載の電動パワーステアリング装置。  2. The electric power steering apparatus according to claim 1, wherein the twisting directions of the inclined teeth are set to be the same direction.
[10] 前記内外歯車の内歯の捩れ角は、 Θ であり、 [10] The twist angle of the internal teeth of the internal and external gears is Θ,
a  a
前記内外歯車の外周面嚙合歯の捩れ角は、 Θ  The torsion angle of the outer peripheral meshing teeth of the inner and outer gears is Θ
bであり、  b,
前記内外歯車の内歯の嚙合いピッチ円半径は、 r  The internal pitch pitch radius of the internal and external gears is r
aであり、  a,
前記内外歯車の外周面嚙合歯と前記ベルトの嚙合歯との嚙合いピッチ円半径は、 rであり、以下の関係を満たすべく θ , Θ , r , rが設定されたことを特徴とする請求 b a b a b  The meshing pitch circle radius between the outer peripheral surface meshing teeth of the internal and external gears and the meshing teeth of the belt is r, and θ, Θ, r, r are set so as to satisfy the following relationship: babab
項 9に記載の電動パワーステアリング装置。  Item 10. The electric power steering device according to Item 9.
(式 4)  (Formula 4)
rh tan 9b r h tan 9 b
r0 tan r 0 tan
[11] 4輪操舵の後輪操舵に用いることを特徴とした請求項 1に記載の電動パワーステアリ ング装置。 11. The electric power steering device according to claim 1, wherein the electric power steering device is used for rear wheel steering of four-wheel steering.
[12] 前記ステアリングホイールと前記ラック軸とが機械的に連結されていない、 ステアバイワイヤ式のステアリングに用いられることを特徴とした請求項 1に記載の電 動パワーステアリング装置。 [12] The steering wheel and the rack shaft are not mechanically connected. 2. The electric power steering apparatus according to claim 1, which is used for steer-by-wire steering.
PCT/JP2005/024142 2004-12-28 2005-12-28 Electric power steering device WO2006070889A1 (en)

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JP2010179891A (en) * 2009-02-09 2010-08-19 Jtekt Corp Electric power steering device
DE102014112253A1 (en) 2013-08-29 2015-03-05 Jtekt Corporation STEERING DEVICE
JP2016055830A (en) * 2014-09-12 2016-04-21 株式会社ショーワ Steering device
JP2016084011A (en) * 2014-10-24 2016-05-19 アイシン精機株式会社 Rear wheel steering device for vehicle
JP2016203758A (en) * 2015-04-21 2016-12-08 アイシン精機株式会社 Rear wheel steering device of vehicle
US11192416B2 (en) * 2017-07-07 2021-12-07 Zf Friedrichshafen Ag Adjusting device for a chassis of a motor vehicle and rear-axle steering system
CN110578779A (en) * 2018-06-08 2019-12-17 操纵技术Ip控股公司 durable power unit belt drive
CN110578779B (en) * 2018-06-08 2023-06-20 操纵技术Ip控股公司 Durable power unit belt drive

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